Ark Globe Academy - Chemistry Year 12 12... · 2020. 4. 20. · Chemistry Year 12 School Closure Pack A timetable has been created for you to ensure that your work is manageable.

Chemistry Year 12 School Closure Pack

A timetable has been created for you to ensure that your

work is manageable. Each day you are expected to complete

1 hr of chemistry work. For each topic:

1. Revise using the online resources (approx. 20 min)

2. Answer and mark all exam questions (approx. 30 min)

3. Add up your total, take a picture of your work and

upload to Edmodo by 3.30pm

You will also have an online quiz every Tuesday and

Thursday.

Resources:

1. chemrevise.org/revision-guides/

2. www.youtube.com/user/MrERintoul/playlists

3. chemguide.co.uk

4. physicsandmathstutor.co.uk

Ms Baig is reachable on Edmodo for feedback, tutorials and to

answer any of your questions, during the school day.

Name………………………………………………………………………………………………………

Year 12 Chemistry

Date Topic Title Work to be completed (Tick)

Resource provided

Outcome Online Support

1 Ch6: Equilibria

o Revise using the online support

o Answer and mark all exam questions

o Add up your total, take a picture and upload to edmodo

-Exam questions and mark scheme

o Detailed understanding of notes

o Marked exam questions

o At least 70% in biweekly chapter quiz

o Chemrevise notes o Edmodo o Eliot Rintoul

YouTube channel o Chemguide o Maths and Physics

Tutor

2 Ch11: Introduction to Organic Chemistry










Tutor

End of day 2 o Complete Edmodo Quiz (on previous 2 chapters atleast)

Edmodo o At least 70% in biweekly chapter quiz

o Edmodo Quiz

3 Ch13: Haloalkanes










Tutor

4 Ch2: Amount of substance










Tutor

End of day 4 o Complete Edmodo Quiz (on previous 2 chapters atleast) by 11pm


o Edmodo Quiz

5 Ch12: Alkanes










Tutor

6 Ch4: Energetics









Tutor

o At least 70% in

biweekly chapter quiz



o Edmodo Quiz

7 Ch14: Alkenes










Tutor

8 Ch3: Bonding o Revise using the online support









Tutor



o Edmodo Quiz

9 Ch8: Periodicity










Tutor

10 Ch9: Group 2










Tutor



o Edmodo Quiz

Resources:

1. https://chemrevise.org/revision-guides/

2. www.youtube.com/user/MrERintoul/playlists

3. chemguide.co.uk

4. physicsandmathstutor.co.uk

1. (a) The diagram below shows the effect of temperature and pressure on the equilibrium yield of the product in a gaseous equilibrium.

Yield/%

Temperature

10 MPa

30 MPa

50 MPa

(i) Use the diagram to deduce whether the forward reaction involves an increase or a decrease in the number of moles of gas. Explain your answer.

Change in number of moles .............................................................................

Explanation ......................................................................................................

...........................................................................................................................

...........................................................................................................................

(ii) Use the diagram to deduce whether the forward reaction is exothermic or endothermic. Explain your answer.

The forward reaction is ....................................................................................

Explanation ......................................................................................................

...........................................................................................................................

........................................................................................................................... (6)

2

(b) When a 0.218 mol sample of hydrogen iodide was heated in a flask of volume V dm3, the following equilibrium was established at 700 K.

2HI(g) H2(g) + I2(g)

The equilibrium mixture was found to contain 0.023 mol of hydrogen.

(i) Calculate the number of moles of iodine and the number of moles of hydrogen iodide in the equilibrium mixture.

Number of moles of iodine..................................................................................

Number of moles of hydrogen iodide.................................................................

...........................................................................................................................

(ii) Write an expression for Kc for the equilibrium.

...........................................................................................................................

...........................................................................................................................

(iii) State why the volume of the flask need not be known when calculating a value for Kc.

...........................................................................................................................

...........................................................................................................................

(iv) Calculate the value of Kc at 700 K.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

(v) Calculate the value of Kc at 700 K for the equilibrium

H2(g) + I2(g) 2HI(g)

...........................................................................................................................

........................................................................................................................... (7)

(Total 13 marks)

3

Sumayya Baig

Text Box

Equilibria

2. Acid X reacts with methanol to form ester Y according to the following equation.

A mixture of 0.25 mol of X and 0.34 mol of methanol was left to reach equilibrium in the presence of a small amount of concentrated sulphuric acid. The equilibrium mixture thus formed contained 0.13 mol of Y in a total volume of V dm3.

(a) Using X to represent the acid and Y to represent the ester, write an expression for the equilibrium constant, Kc, for this reaction.

(1)

(b) Calculate the number of moles of X, the number of moles of methanol and the number of moles of water in the equilibrium mixture.

Moles of X ..............................................................................................................

Moles of methanol ...................................................................................................

Moles of water ......................................................................................................... (3)

(c) State why the volume V need not be known in calculating the value of Kc for the reaction.

................................................................................................................................

................................................................................................................................ (1)

(d) Calculate the value of Kc for this reaction and deduce its units.

Calculation .............................................................................................................

................................................................................................................................

................................................................................................................................

................................................................................................................................

Units of Kc ..............................................................................................................

................................................................................................................................ (3)

(e) State the effect, if any, of increasing the temperature on the value of Kc

................................................................................................................................ (1)

(Total 9 marks)

C H C O O H C H C O O C H

C H C O O H C H C O O C H + 2 C H O H + 2 H O ∆ H = – 1 5 k J m o l

2 2 3 3 2 – 1 2 2 3

a c i d X e s t e r Y

4

3. As a first step in the manufacture of nitric acid it has been suggested that nitrogen monoxide, NO, can be formed from nitrogen and oxygen in a reversible reaction.

(a) Write an equation for this reaction and deduce an expression for the equilibrium constant, Kc

Equation.......................................................................................................................

Kc ................................................................................................................................ (2)

(b) The sketch graph below shows how the value of Kc for this reaction changes with temperature.

Kc

Temperature

Use this graph to deduce whether the reaction is exothermic or endothermic.

Explain your answer.

.....................................................................................................................................

..................................................................................................................................... (2)

(c) The value of Kc for this reaction is 1 × 10–5 at 1500 K.

Explain the significance of this value for an industrial chemist interested in manufacturing nitrogen monoxide by the direct combination of the elements.

.....................................................................................................................................

..................................................................................................................................... (2)

5

(d) When cooled, nitrogen monoxide reacts with oxygen to form gaseous nitrogen dioxide, NO2, in a reversible reaction.

(i) Write an equation for this reaction.

...........................................................................................................................

(ii) State how an increase in pressure would change the position of the equilibrium and the value of the equilibrium constant for this reaction.

Change in equilibrium position.........................................................................

Change in equilibrium constant........................................................................ (3)

(Total 9 marks)

6

4. The manufacture of methanol can be achieved in two stages.

In the first stage, methane and steam react according to the following equation.

CH4(g) + H2O(g) CO(g) + 3H2(g) ∆Hο = +210 kJ mol–1

Discuss, with reasons, the effects of increasing separately the temperature and the pressure on the yield of the products and on the rate of this reaction.

(6) (Total 6 marks)

5. The reaction between hydrogen and iodine can be represented by the following equation:

H2(g) + I2(g) 2HI(g) ∆H = +52 kJ mol–1 (a) Write a Kc expression for the decomposition of hydrogen iodide. At a given temperature, the

value of Kc for this reaction is 20. What will be the value of Kc for the reaction between hydrogen and iodine at this temperature?

(2)

(b) The pressure of an equilibrium mixture of hydrogen iodide, hydrogen and iodine was increased. State what, if anything, would happen to:

(i) the rates of both forward and reverse reactions; (2)

(ii) the position of equilibrium; (1)

(iii) the value of the equilibrium constant. (1)

(Total 6 marks)

7

4.2 ANSWERS TO EXAM QUESTIONS

1. (a) (i) Increase (if wrong no further marks in part (i) 1 higher P gives lower yield or moves to left 1 Eqm shifts to reduce P or eqm favours side with fewer moles 1

(ii) Endothermic if wrong no further marks in part (ii) 1 increase T increases yield or moves to right 1 Eqm shifts to reduce T or eqm favours endothermic direction 1

(b) (i) Moles of iodine = 0.023 1 Moles of HI = 0.172 1 If × 2 missed, max 1 in part (iv)

If wrong no marks in (i)

(ii) Kc = 222

HI][]I][H[ must be square brackets (penalise once in paper) 1

– if round, penalise but mark on in (iv) if Kc wrong, no marks in (iv) either but mark on from a minor slip in formula

(iii) V cancels in Kc expression or no moles same on top and bottom of expression or total moles reactants = moles products, i.e. total no of moles does not change 1

(iv) Kc = 2

2

)172.0()023.0(

1

= 0.0179 or 1.79 × 10–2

Conseq on (i) 1 Allow 0.018 or 1.8 × 10–2

(v) Kc = 55.9 or 56 1 Conseq i.e. (answer to (iv))–1

[13]

2. (a) Kc = 23

22

OH][CH [X]O][H [Y]

(1)

if Kc expression wrong lose units mark in (e) also must be [ ]

1

(b) Moles of X: 0.25 - 0.13 = 0.12 (1) Moles of methanol: 0.34 - 0.26 = 0.08 (1) Moles of water: 0.26 (1) 3

(c) Equal no. of moles on each side of equation (1) OR V cancels out (provided not incorrectly qualified)

1

1

(d) Calculation: Kc = 2

2

V0.08

V0.12

V0.26

V0.13

(1)

= 11(.4) (1) Can score all 3 conseq on (b) and (c) If different values from (c) used allow units only (conseq on correct Kc)

Units of Kc: none (1) but lose this mark if Kc is wrong even if none given

3

(e) decrease (1) 1 [9]

3. (a) Equation N2 + O2 2NO (1) Kc [NO]2 / [N2] [O2] (1) 2

(b)

Kc

Temperature As temperature increases Kc increases (or yield increases) (1)

Hence reaction endothermic (1) 2

(c) The product yield is very small (1) Yield does not justify cost of producing high temp (1) 2

(d) (i) 2NO + O2 2NO2 (1)

(ii) Change in equilibrium position Displaced to the right (1) Change in equilibrium constant No change (1) 3

[9]

2

4. (must state correct effect on yield or rate to score the reason mark)

T effect: higher temp: yield greater or shifts equilibrium to right; 1 effect: higher temp: rate increased; 1 reason: endothermic

OR

more particles have E>Ea 1

OR

more successful/productive collisions; 1

P effect: higher pressure: yield less or shifts equilibrium to left; 1

effect: higher pressure: rate increased;

reason: increase in gas moles L to R

OR

greater collision frequency; 1

(Q of L mark)

[6]

5. (a) Kc = 2

22

[HI]]][I[H (1)

0.05 or 1/20 (1) 2

(b) (i) forward rate increases (1)

reverse rate increases (1)

allow 1 mark for just ‘increased’ allow 2 marks for ‘both increased’ 2

(ii) no change (1) 1

(iii) no change (1) 1 [6]

6. (a) (i) Moles NaOH = mv/1000 = 1.50 × 72.5/1000 = 0.108 to 0.11 (1) Moles of ethanoic acid at equilibrium = moles sodium hydroxide (1) Moles ester = moles water (=moles acid reacted) (1) = 0.200 – 0.108 = 0.090 to 0.92 (1) Moles ethanol = 0.110 – 0.091 = 0.018 to 0.020 (1) KC = [Ester] [Water]/[Acid] [Alcohol] (1)

Allow if used correctly

= (0.091)2/0.109 × 0.019 = 3.7 to 4.9 (1) 7 Ignore units NB Allow the answer 4 one mark as correct knowledge

(ii) Similar (types) of bond broken and made (1) Same number of the bonds broken and made (1) 2

any number if equal NB If a list given then the total number of each type of bond

broken and made must be the same

[9]

3

7. (a) Homogeneous; All reactants in the same phase or state (1)

Dynamic; Continuous or 'on-going' (1)

Equilibrium: Concentrations of reactants and products constant or rates of forward and backward reactions equal (1)

Equation; 2NH3 N2 + 3H2 (Must be decomposition) (1)

Kc; [N2][H2]3/[NH3]2 (1) 5

(b) Conditions: decomposition favoured by high temp (1)

since the reaction endothermic or logical statement with application of Le Chatelier's principle (1)

decomposition favoured by low pressure (1)

2 mole gas giving 4 moles gas or more gas moles on right (1)

4

(c) In practise low pressure means low production (1) low pressure means low rate (1)

high temperature means high rate (1) high temperature expensive (1)

Catalyst equilibrium yield unaffected (1) rates of forward and backwards reactions increased by an equal amount (1) more hydrogen produced in a given time (1)

Max 6 [15]

4

Page 2

Q1.The carboxylic acid 3-methylbutanoic acid is used to make esters for perfumes. The following scheme shows some of the reactions in the manufacture of this carboxylic acid.

(a) One of the steps in the mechanism for Reaction 1 involves the replacement of the functional group by bromine.

(i) Use your knowledge of organic reaction mechanisms to complete the mechanism for this step by drawing two curly arrows on the following equation.

(2)

(ii) Deduce the name of the mechanism in part (i).

Give the IUPAC name of (CH3)2CHCH2Br

...............................................................................................................

...............................................................................................................

............................................................................................................... (2)

(b) Reaction 3 is an acid-catalysed reaction in which water is used to break chemical bonds when the CN functional group is converted into the COOH functional group. Infrared spectroscopy can be used to distinguish between the compounds in this reaction.

PhysicsAndMathsTutor.com

Page 3

Deduce the name of the type of reaction that occurs in Reaction 3.

Identify one bond in (CH3)2CHCH2CN and a different bond in (CH3)2CHCH2COOH that can be used with infrared spectroscopy to distinguish between each compound. For each of these bonds, give the range of wavenumbers at which the bond absorbs. Use Table A on the Data Sheet when answering this question.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (3)

(c) When 3-methylbutanoic acid reacts with ethanol in the presence of an acid catalyst, an equilibrium is established. The organic product is a pleasant-smelling ester.

(CH3)2CHCH2COOH + CH3CH2OH

(CH3)2CHCH2COOCH2CH3

an ester + H2O

The carboxylic acid is very expensive and ethanol is inexpensive. In the manufacture of this ester, the mole ratio of carboxylic acid to ethanol used is 1 to 10 rather than 1 to 1.

(i) Use Le Chatelier’s principle to explain why a 1 to 10 mole ratio is used. In your explanation, you should not refer to cost.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

(Extra space) ..........................................................................................


Sumayya Baig

Text Box

Introduction to Organic Chemistry

Page 4

............................................................................................................... (3)

(ii) Explain how a catalyst increases the rate of a reaction.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

(Extra space) .........................................................................................

............................................................................................................... (2)

(Total 12 marks)

Q2.(a) The hydrocarbon but-1-ene (C4H8) is a member of the homologous series of alkenes. But-1-ene has structural isomers.

(i) State the meaning of the term structural isomers.

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (2)

(ii) Give the IUPAC name of the position isomer of but-1-ene.

............................................................................................................... (1)

(iii) Give the IUPAC name of the chain isomer of but-1-ene.

............................................................................................................... (1)


Page 5

(iv) Draw the displayed formula of a functional group isomer of but-1-ene. (1)

(b) But-1-ene burns in a limited supply of air to produce a solid and water only.


............................................................................................................... (1)

(ii) State one hazard associated with the solid product in part (b)(i).

............................................................................................................... (1)

(c) One mole of compound Y is cracked to produce two moles of ethene, one mole of but-1-ene and one mole of octane (C8H18) only.

(i) Deduce the molecular formula of Y.

............................................................................................................... (1)

(ii) Other than cracking, give one common use of Y.

............................................................................................................... (1)

(d) In cars fitted with catalytic converters, unburned octane reacts with nitrogen monoxide to form carbon dioxide, water and nitrogen only.


............................................................................................................... (1)

(ii) Identify a catalyst used in a catalytic converter.

...............................................................................................................


Page 6

(1) (Total 11 marks)

Q3.(a) The structure of the bromoalkane Z is

Give the IUPAC name for Z.

Give the general formula of the homologous series of straight-chain bromoalkanes that contains one bromine atom per molecule.

Suggest one reason why 1-bromohexane has a higher boiling point than Z.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

(Extra space) ................................................................................................

........................................................................................................................

........................................................................................................................ (3)

(b) Draw the displayed formula of 1,2-dichloro-2-methylpropane.

State its empirical formula.


Page 7

........................................................................................................................

........................................................................................................................ (2)

(Total 5 marks)

Q4. Pentane is a member of the alkane homologous series.

(a) Give the general formula for the homologous series of alkanes.

..................................................................................................................... (1)

(b) One of the structural isomers of pentane is 2,2-dimethylpropane.

Draw the displayed formula of 2,2-dimethylpropane.

State the type of structural isomerism shown.

..................................................................................................................... (2)

(c) A molecule of hydrocarbon Y can be thermally cracked to form one molecule of pentane and two molecules of ethene only.

Deduce the molecular formula of Y.

State why high temperatures are necessary for cracking reactions to occur.

Give one reason why thermal cracking reactions are carried out in industry.

.....................................................................................................................


Page 2

M1.(a) (i) M1 double-headed curly arrow from the lone pair of the bromide ion to the C atom of the CH2

Penalise additional arrows.

M2 double-headed arrow from the bond to the O atom

As follows

2

(ii) M1 nucleophilic substitution M1 both words needed (allow phonetic spelling).

M2 1-bromo(-2-)methylpropane M2 Require correct spelling in the name but ignore any hyphens or commas.

2

(b) M1 hydrolysis For M1 give credit for ‘hydration’ on this occasion only.

M2 C≡N with absorption range 2220–2260 (cm−1) Credit 1 mark from M2 and M3 for identifying C≡N and either O–H(acids) or C=O or C–O without reference to wavenumbers or with incorrect wavenumbers.

M3 O–H(acids) with absorption range 2500–3000 (cm−1)

OR

C=O with absorption range 1680–1750 (cm−1)

OR

C–O with absorption range 1000–1300 (cm−1) Apply the list principle to M3

3

(c) (i) M1 Yield / product OR ester increases / goes up / gets more

M2 (By Le Chatelierߣs principle) the position of equilibrium is driven / shifts / moves to the right / L to R / in the forward direction / to the


Page 3

product(s)

M3 – requires a correct statement in M2

(The position of equilibrium moves)

to oppose the increased concentration of ethanol

to oppose the increased moles of ethanol

to lower the concentration of ethanol

to oppose the change and decrease the ethanol If no reference to M1, marks M2 and M3 can still score BUT if M1 is incorrect CE=0 If there is reference to ‘pressure’ award M1 ONLY.

3

(ii) M1

Catalysts provide an alternative route / pathway / mechanism

OR

surface adsorption / surface reaction occurs For M1, not simply ‘provides a surface’ as the only statement. M1 may be scored by reference to a specific example.

M2

that has a lower / reduced activation energy

OR

lowers / reduces the activation energy Penalise M2 for reference to an increase in the energy of the molecules. For M2, the student may use a definition of activation energy without referring to the term. Reference to an increase in successful collisions in unit time alone is not sufficient for M2 since it does not explain why this has occurred.

2

[12]

M2.(a) (i) (Compounds with the) same molecular formula Allow same number and type of atom for M1


Page 4

Ignore same general formula. 1

But different structural formula / different displayed formula / different structures / different skeletal formula

M2 dependent on M1 Not different positions of atoms / bonds in space.

1

(ii) But-2-ene Allow but-2-ene. Allow but 2 ene. Ignore punctuation.

1

(iii) (2)-methylprop-(1)-ene Do not allow 2-methyleprop-1-ene.

1

(iv)

Do not allow skeletal formulae. Penalise missing H and missing C

1

(b) (i) C4H8 + 2O2 → 4C + 4H2O Accept multiples.

1


Page 5

(ii) Exacerbates asthma / breathing problems / damages lungs / smog / smoke / global dimming

Ignore toxic / pollutant / soot / carcinogen. Do not allow greenhouse effect / global warming / acid rain / ozone.

1

(c) (i) C16H34

Allow H34C16

C and H must be upper case. 1

(ii) Jet fuel / diesel / (motor) fuel / lubricant / petrochemicals / kerosene / paraffin / central heating fuel / fuel oil

Ignore oil alone. Not petrol / bitumen / wax / LPG / camping fuel.

1

(d) (i) C8H18 + 25NO → 8CO2 + 12.5 N2 + 9H2O Accept multiples.

1

(ii) Ir / iridium

OR

Pt / platinum

OR

Pd / palladium

OR

Rh / rhodium 1

[11]


Page 6

M3.(a) 2-bromo-2,3-dimethylbutane Ignore punctuation.

1

CnH2n+1Br or CnH 2n+1X or CxH2x+1Br Any order.

1

Stronger / more vdw (forces) between molecules (of 1-bromohexane) QoL Allow converse arguments for Z Not just more IMF. Ignore size of molecule.

1

(b)

1

C2H4Cl Any order

1

[5]

M4. (a) Cn H2n+2

Allow x in place of n 1


Page 7

(b)

Chain Must show every bond Allow branched chain

2

(c) C9H20

Only 1

To break the (C-C and/or C-H) bonds M2=0 if break C=C

1

To make products which are in greater demand / higher value / make alkenes

Not more useful products Allow specific answers relating to question

1

(d) C5H12 + 3O2 → 5C + 6H2O Allow other balanced equations which give C and CO/CO2

1

Causes global dimming / exacerbates asthma / causes breathing problems / makes visibility poor / smog

Apply list principle Ignore causes cancer / toxic

1

(e) (x 100)


Page 2

Q1. (a) Compounds with double bonds between carbon atoms can exhibit geometrical isomerism.

(i) Draw structures for the two geometrical isomers of 1,2-dichloroethene.

Isomer 1 Isomer 2

(ii) What feature of the double bond prevents isomer 1 from changing into isomer 2?

............................................................................................................. (3)

(b) When 2-chloropropane reacts with sodium hydroxide, two different reactions occur. Each reaction produces a different organic product.

(i) Outline a mechanism for Reaction 1 and state the role of the hydroxide ion in this reaction.

Mechanism

Role of the hydroxide ion ....................................................................


Page 3

(ii) Outline a mechanism for Reaction 2 and state the role of the hydroxide ion in this reaction.

Mechanism

Role of the hydroxide ion .................................................................... (7)

(Total 10 marks)

Q2. (a) Propene reacts with hydrogen bromide by an electrophilic addition mechanism forming 2-bromopropane as the major product.

The equation for this reaction is shown below.

(i) Outline the mechanism for this reaction, showing the structure of the intermediate carbocation formed.


Sumayya Baig

Text Box

Haloalkanes

Page 4

(ii) Give the structure of the alternative carbocation which could be formed in the reaction between propene and hydrogen bromide.

(5)

(b) A substitution reaction occurs when 2-bromopropane reacts with aqueous sodium hydroxide.

(i) Draw the structure of the organic product of this reaction and give its name.

Structure

Name ..................................................................................................

(ii) Name and outline the mechanism for this reaction.

Name of mechanism ...........................................................................


Page 5

Mechanism

(5)

(c) Under different conditions, 2-bromopropane reacts with sodium hydroxide to produce propene.

(i) Name the mechanism for this reaction.

.............................................................................................................

(ii) State the role of sodium hydroxide in this reaction.

............................................................................................................. (2)

(Total 12 marks)

Q3.Which one of the following types of reaction mechanism is not involved in the above sequence?

CH3CH2CH3 (CH3)2CHCl (CH3)2CHCN

(CH3)2CHCH2NHCOCH3 (CH3)2CHCH2NH2

A free-radical substitution


Page 6

B nucleophilic substitution

C elimination

D nucleophilic addition-elimination (Total 1 mark)

Q4. The conversion of compound A into compound B can be achieved in two steps as shown below.

The intermediate compound, X, has an absorption at 1650 cm–1 in its infra-red spectrum.

(a) Identify compound X. Explain your answer. (2)

(b) For each step in this conversion, give the reagents and essential conditions required and outline a mechanism.

(11)

(c) Show how the number of peaks in their proton n.m.r. spectra would enable you to distinguish between compounds A and B.

(2) (Total 15 marks)


Page 2

M1. (a) (i)

(ii) restricted rotation OR no rotation OR cannot rotate (1) 3

(b) (i) Mechanism:

M1 and M2 independent Curly arrows must be from a bond or a lone pair Do not penalise sticks

Penalise M1 if precedes (penalise this once) Penalise incorrect δ+ δ– for M2 Penalise + on C atom for M2 Only allow M1 for incorrect haloalkane

Role of the hydroxide ion: nucleophile (1) electron pair donor lone pair donor

NOT nucleophilic substitution


Page 3

(ii) Mechanism:

Only allow M1 and M2 for incorrect haloalkane unless RE on (i) + charge on H on molecule, penalise M1 M3 independent M2 must be to correct C–C M1 must be correct H atom Credit M1 and M2 via carbocation mechanism No marks after any attack of C by OH–

Role of the hydroxide ion: base (1) proton acceptor accepts H+

7

[10]

M2. (a) (i)


Page 4

If wrong carbocation, lose structure mark If wrong alkene, lose structure mark Can still score ¾ i.e. penalise M3 Penalise M2 if polarity included incorrectly no bond between H and Br bond is shown as or

(ii) credit secondary carbocation here if primary carbocation has been used in (i)

Ignore attack on this carbocation by 5

(b) (i) Structure:

No credit for propan-1-ol even when named correctly Credit propane-2-ol

Name: propan-2-ol (1)

Not 2-hydroxypropane

(ii) Name of mechanism: nucleophilic substitution (1) (both words) (NOT SN1 orSN2)

Mechanism:


Page 5

penalise incorrect polarity on C‑ Br (M1) Credit the arrows even if incorrect haloalkane If SN1, both marks possible

5

(c) (i) elimination (1) Ignore nucleophylic elimination Penalise electrophilic elimination

(ii) base (1)

OR proton acceptor NOT nucleophile (base)

2

[12]

M3.C

[1]

M4. (a) Identity of X; 2-methylpropene (1) Absorption at 1650 cm–1 indicates an alkene present (1)

OR a chemical answer e.g. Br2 (aq) brown to colourless 2

(b) Reagents Step 1 KOH (allow NaOH) (1) alcoholic (1) warm (1)

Only allow solvent and warm if reagent correct


Page 6

Step 2 HBr (1)

Mechanism: A → X

Or a carbocation mechanism

Mechanism X → B

11

(c) A gives three peaks (1) B gives one peak (1)

Allow one for “A has more peaks than B” when no number of peaks is given

2

[15]


Page 2

Q1.Some airbags in cars contain sodium azide (NaN3).

(a) Sodium azide is made by reacting dinitrogen monoxide gas with sodium amide (NaNH2) as shown by the equation.

2NaNH2 + N2O NaN3 + NaOH + NH3

Calculate the mass of sodium amide needed to obtain 550 g of sodium azide, assuming there is a 95.0% yield of sodium azide. Give your answer to 3 significant figures.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (5)

(b) If a car is involved in a serious collision, the sodium azide decomposes to form sodium and nitrogen as shown in the equation.

2NaN3(s) 2Na(s) + 3N2(g)

The nitrogen produced then inflates the airbag to a volume of 7.50 × 10−2 m3 at a pressure of 150 kPa and temperature of 35 °C.

Calculate the minimum mass of sodium azide that must decompose. (The gas constant R = 8.31 J K−1 mol−1)

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................


Page 3

........................................................................................................................

........................................................................................................................

........................................................................................................................ (6)

(c) Sodium azide is toxic. It can be destroyed by reaction with an acidified solution of nitrous acid (HNO2) as shown in the equation.

2NaN3 + 2HNO2 + 2HCl 3N2 + 2NO + 2NaCl + 2H2O

(i) A 500 cm3 volume of the nitrous acid solution was used to destroy completely 150 g of the sodium azide.

Calculate the concentration, in mol dm−3, of the nitrous acid used.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (3)

(ii) Nitrous acid decomposes on heating.

Balance the following equation for this reaction.

........HNO2 .......HNO3 + .......NO + .......H2O (1)

(d) Sodium azide has a high melting point.

Predict the type of bonding in a crystal of sodium azide. Suggest why its melting point is high.

Type of bonding .............................................................................................

Reason for high melting point ........................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................


Sumayya Baig

Text Box

Amount of substance

Page 4

........................................................................................................................ (3)

(e) The azide ion has the formula N3−

(i) The azide ion can be represented as N N − N−

One of these bonds is a co−ordinate bond.

On the following diagram, draw an arrowhead on one of the bonds to represent the direction of donation of the lone pair in the co−ordinate bond.

N N − N− (1)

(ii) Give the formula of a molecule that has the same number of electrons as the azide ion.

............................................................................................................... (1)

(iii) Which is the correct formula of magnesium azide?

Tick (✓) one box.

Mg3N

MgN

MgN6

Mg3N2

(1)

(Total 21 marks)

Q2.A sample of pure Mg(NO3)2 was decomposed by heating as shown in the equation below.


Page 5

2Mg(NO3)2(s) 2MgO(s) + 4NO2(g) + O2(g)

(a) A 3.74 × 10−2 g sample of Mg(NO3)2 was completely decomposed by heating.

Calculate the total volume, in cm3, of gas produced at 60.0 °C and 100 kPa. Give your answer to the appropriate number of significant figures. The gas constant R = 8.31 J K−1 mol−1.

Total volume of gas = ...................... cm3

(5)

(b) The mass of MgO obtained in this experiment is slightly less than that expected from the mass of Mg(NO3)2 used. Suggest one practical reason for this.

........................................................................................................................

........................................................................................................................

........................................................................................................................ (1)

(Total 6 marks)

Q3.Calamine lotion can contain a mixture of zinc carbonate and zinc oxide in suspension in water. A manufacturer of calamine lotion claims that a sample contains 15.00 g of zinc carbonate and 5.00 g of zinc oxide made up to 100 cm3 with distilled water.

(a) A chemist wanted to check the manufacturer’s claim. The chemist took a 20.0 cm3 sample of the calamine lotion and added it to an excess of sulfuric acid. The volume of carbon dioxide evolved was measured over time. The chemist’s results are shown in the table.

Time / s 0 15 30 45 60 75 90 105 120 135

Volume / cm3 0 135 270 380 470 530 560 570 570 570


Page 6

(i) Plot a graph of the results in the table on the grid. The volume should be on the y-axis. Draw a best-fit curve through all the points.

(3)

(ii) Estimate the time taken for the reaction to be completed.

............................................................................................................... (1)


Page 7


Page 2

M1.(a) M1 550 × = 579 g would be 100% mass Allow alternative methods.

There are 4 process marks: 1

M2 So = 8.91 moles NaN3

or

M1 = 8.46 moles NaN3 (this is 95%)

M2 So 100% would be 8.46 × = 8.91 moles NaN3

1: mass ÷ 65

2: mass or moles × 100 / 95 or × 1.05

3: moles NaN3 × 2

4: moles NaNH2 × 39 1

Then M3 Moles NaNH2 = 8.91 × 2 = ( 17.8(2) moles) 1

M4 mass NaNH2 = 17.8(2) × 39 1

M5 693 or 694 or 695 (g) If 693, 694 or 695 seen to 3 sig figs award 5 marks

1

(b) M1 308 K and 150 000 Pa 1

M2 n = or 1

M3 = 4.4(0) or 4.395 moles N2

Allow only this answer but allow to more than 3 sig figs 1


Page 3

M4 Moles NaN3 = 4.395 × (= 2.93)

M4 is for M3 × 1

M5 Mass NaN3 = (2.93) × 65 M5 is for moles M4 × 65

1

M6 = 191 g Allow 190 to 191 g allow answers to 2 sig figs or more

1

(c) (i) 150 / 65 = 2.31 moles NaN3 or 2.31 moles nitrous acid 1

Conc = 2.31 ×

M2 is for M1 × 1000 / 500 1

4.6(1) or 4.6(2) (mol dm−3) Only this answer

1

(ii) 3HNO2 HNO3 + 2NO + H2O

Can allow multiples 1

(d) Ionic If not ionic then CE = 0 / 3

1

Oppositely charged ions / Na+ and N3 − ions Penalise incorrect ions here but can allow M3

1

Strong attraction between (oppositely charged) ions / lots of energy needed to overcome (strong) attractions (between ions)

M3 dependent on M2 1

(e) (i) N ≡ N N−

Only 1


Page 4

(ii) CO2 / N2O / BeF2 / HN3

Allow other correct molecules 1

(iii) MgN6

Only 1

[21]

M2.(a) Stage 1

Mr for Mg(NO3)2 = 148.3

Moles of Mg(NO3)2 = = 2.522 × 10-4 mol Extended response calculation

1

Stage 2

Total moles of gas produced = 5/2 × moles of Mg(NO3)2

= 5/2 × 2.522 × 10–4 = 6.305 × 10–4

If ratio in stage 2 is incorrect, maximum marks for stage 3 is 2

1

Stage 3

PV = nRT so volume of gas V = nRT / P 1

V = = 1.745 × 10–5 m3

1

V = 1.745 × 10–5 × 1 × 106 = 17.45 cm3 = 17.5 (cm3) Answer must be to 3 significant figures (answer could be 17.4 cm3 dependent on intermediate values)

1


Page 5

(b) Some of the solid is lost in weighing product / solid is blown away with the gas 1

[6]

M3.(a) (i) Uses sensible scales. Lose this mark if the plotted points do not cover half of the paper.

Lose this mark if the graph plot goes off the squared paper

Lose this mark if volume is plotted on the x-axis 1

All points plotted correctly Allow ± one small square.

1

Smooth curve from 0 seconds to at least 135 seconds − the line must pass through or close to all points (± one small square).

Make some allowance for the difficulties of drawing a curve but do not allow very thick or doubled lines.

1

(ii) Any value in the range 91 to 105 s Allow a range of times within this but not if 90 quoted.

1

(b) (i) Using pV = nRT This mark can be gained in a correctly substituted equation.

1

100 000 × 570 × 10−6 = n × 8.31 × 293 Correct answer with no working scores one mark only.

1

n = 0.0234 mol Do not penalise precision of answer but must have a minimum of 2 significant figures.

1

(ii) Mol of ZnCO3 = 0.0234 Mark consequentially on Q6

M1 1

Mass of ZnCO3 = M1 × 125.4 = 2.9(3) or 2.9(4) g If 0.0225 used then mass = 2.8(2) g


Page 2

Q1.(a) The hydrocarbon but-1-ene (C4H8) is a member of the homologous series of alkenes. But-1-ene has structural isomers.

(i) State the meaning of the term structural isomers.

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (2)

(ii) Give the IUPAC name of the position isomer of but-1-ene.

............................................................................................................... (1)

(iii) Give the IUPAC name of the chain isomer of but-1-ene.

............................................................................................................... (1)

(iv) Draw the displayed formula of a functional group isomer of but-1-ene. (1)

(b) But-1-ene burns in a limited supply of air to produce a solid and water only.


............................................................................................................... (1)

(ii) State one hazard associated with the solid product in part (b)(i).

............................................................................................................... (1)


Page 3

(c) One mole of compound Y is cracked to produce two moles of ethene, one mole of but-1-ene and one mole of octane (C8H18) only.

(i) Deduce the molecular formula of Y.

............................................................................................................... (1)

(ii) Other than cracking, give one common use of Y.

............................................................................................................... (1)

(d) In cars fitted with catalytic converters, unburned octane reacts with nitrogen monoxide to form carbon dioxide, water and nitrogen only.


............................................................................................................... (1)

(ii) Identify a catalyst used in a catalytic converter.

............................................................................................................... (1)

(Total 11 marks)

Q2.The following table shows the boiling points of some straight-chain alkanes.

CH4 C2H6 C3H8 C4H10 C5H12

Boiling point / °C −162 −88 −42 −1 36

(a) State a process used to separate an alkane from a mixture of these alkanes.

........................................................................................................................ (1)

(b) Both C3H8 and C4H10 can be liquefied and used as fuels for camping stoves.


Sumayya Baig

Text Box

Alkanes

Page 4

Suggest, with a reason, which of these two fuels is liquefied more easily.

........................................................................................................................

........................................................................................................................

........................................................................................................................ (1)

(c) Write an equation for the complete combustion of C4H10

........................................................................................................................ (1)

(d) Explain why the complete combustion of C4H10 may contribute to environmental problems.

........................................................................................................................

........................................................................................................................

........................................................................................................................ (1)

(e) Balance the following equation that shows how butane is used to make the compound called maleic anhydride.

..........CH3CH2CH2CH3 + .......... O2 ..........C2H2(CO)2O + .......... H2O (1)

(f) Ethanethiol (C2H5SH), a compound with an unpleasant smell, is added to gas to enable leaks from gas pipes to be more easily detected.

(i) Write an equation for the combustion of ethanethiol to form carbon dioxide, water and sulfur dioxide.

............................................................................................................... (1)

(ii) Identify a compound that is used to react with the sulfur dioxide in the products of combustion before they enter the atmosphere.

Give one reason why this compound reacts with sulfur dioxide.


Page 5

Substance .....................................................................................................

Reason ..........................................................................................................

........................................................................................................................ (2)

(iii) Ethanethiol and ethanol molecules have similar shapes.

Explain why ethanol has the higher boiling point.

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (2)

(g) The following compound X is an isomer of one of the alkanes in the table on above.

(i) Give the IUPAC name of X.

............................................................................................................... (1)

(ii) X has a boiling point of 9.5 °C.

Explain why the boiling point of X is lower than that of its straight-chain isomer.

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (2)


Page 6

(iii) The following compound Y is produced when X reacts with chlorine.

Deduce how many other position isomers of Y can be formed. Write the number of other position isomers in this box.

(1)

(h) Cracking of one molecule of an alkane Z produces one molecule of ethane, one molecule of propene and two molecules of ethene.

(i) Deduce the molecular formula of Z.

............................................................................................................... (1)

(ii) State the type of cracking that produces a high proportion of ethene and propene. Give the two conditions for this cracking process.

Type of cracking ...................................................................................

Conditions .............................................................................................

............................................................................................................... (2)

(Total 17 marks)

Q3.Hexane (C6H14) is a member of the homologous series of alkanes.

(a) (i) Name the raw material from which hexane is obtained.

............................................................................................................... (1)


Page 7

(ii) Name the process used to obtain hexane from this raw material.

............................................................................................................... (1)

(b) C6H14 has structural isomers.

(i) Deduce the number of structural isomers with molecular formula C6H14

Write the number in this box.

(Space for working)

(1)

(ii) State one type of structural isomerism shown by the isomers of C6H14

............................................................................................................... (1)

(c) One molecule of an alkane X can be cracked to form one molecule of hexane and two molecules of propene.

(i) Deduce the molecular formula of X.

...............................................................................................................

............................................................................................................... (1)

(ii) State the type of cracking that produces a high percentage of alkenes. State the conditions needed for this type of cracking.


Page 2

M1.(a) (i) (Compounds with the) same molecular formula Allow same number and type of atom for M1 Ignore same general formula.

1

But different structural formula / different displayed formula / different structures / different skeletal formula

M2 dependent on M1 Not different positions of atoms / bonds in space.

1

(ii) But-2-ene Allow but-2-ene. Allow but 2 ene. Ignore punctuation.

1

(iii) (2)-methylprop-(1)-ene Do not allow 2-methyleprop-1-ene.

1

(iv)

Do not allow skeletal formulae. Penalise missing H and missing C

1


Page 3

(b) (i) C4H8 + 2O2 → 4C + 4H2O Accept multiples.

1

(ii) Exacerbates asthma / breathing problems / damages lungs / smog / smoke / global dimming

Ignore toxic / pollutant / soot / carcinogen. Do not allow greenhouse effect / global warming / acid rain / ozone.

1

(c) (i) C16H34

Allow H34C16

C and H must be upper case. 1

(ii) Jet fuel / diesel / (motor) fuel / lubricant / petrochemicals / kerosene / paraffin / central heating fuel / fuel oil

Ignore oil alone. Not petrol / bitumen / wax / LPG / camping fuel.

1

(d) (i) C8H18 + 25NO → 8CO2 + 12.5 N2 + 9H2O Accept multiples.

1

(ii) Ir / iridium

OR

Pt / platinum

OR

Pd / palladium

OR

Rh / rhodium 1


Page 4

[11]

M2.(a) Fractional distillation / fractionation / GLC / gas liquid chromatography 1

(b) C4H10

Need C4H10 and the reason for the mark

Because it has a higher bp / has stronger IMF / larger molecule / longer chain / larger surface (area)

1

(c) C4H10 + 6½ O2 4CO2 + 5H2O Accept multiples Ignore state symbols

1

(d) CO2 or H2O evolved is a greenhouse gas / CO2 or H2O evolved contribute to global warming / the products are greenhouse gases

Ignore climate change 1

(e) CH3CH2CH2CH3 + 3.5O2 C2H2(CO)2O + 4H2O Accept multiples Allow with or without a number 1 before the organic molecules

1

(f) (i) C2H5SH + 4.5O2 2CO2 + 3H2O + SO2

Accept multiples 1

(ii) Calcium oxide / calcium carbonate Allow any base or alkali Allow correct formulae

1


Page 5

Neutralises the SO2 / acid base reaction / it is a base Can only score M2 if base or alkali used in M1 Allow M2 if blank in M1

1

(iii) Ethanol contains hydrogen bonding Breaking covalent bonds CE = 0 / 2

Which is stronger than IMF (VDW / dipole-dipole forces) in ethanethiol / (H bonding) is the strongest IMF

Only award M2 if M1 given, but allow IMF in ethanol are stronger than in ethanethiol for maximum 1 mark

1

(g) (i) (2,2-)dimethylpropane Ignore punctuation

1

(ii) Because molecule is smaller / less polarisable / has less surface (area) / is more spherical / molecules can’t get as close to one another (to feel the vdW forces)

Allow converse answers referring to straight chain isomers CE = 0 / 2 if breaking bonds

1

vdW intermolecular forces or vdW force between molecules are weaker or fewer

Need vdW rather than just IMF 1

(iii) 1 or one 1

(h) (i) C9H20

H20C9

1


Page 6

(ii) Thermal (cracking) If not thermal cracking CE = 0 / 2

1

High pressure AND high temperature If blank mark on Allow high P and T

1

OR

Pressure of ≥ 10 atm, ≥ 1 MPa ≥ 1000 kPa

AND temp of 400 °C ≤ T ≤ 1000 °C or 650 K ≤ T≤ 1300 K Do not allow high heat If no units for T, then range must be 650 − 1000

1

[17]

M3.(a) (i) Crude oil / oil / petroleum Do not allow ‘petrol’

1

(ii) Fractional distillation / fractionation / fractionating Not distillation alone

1

(b) (i) 5 Allow five / V

1

(ii) Chain (isomerism) Allow branched chain / chain branched / side chain (isomerism) Ignore position (isomerism) Do not allow straight chain / geometric / branched / function

1


Page 7

(c) (i) C12H26 / H26C12

Only 1

(ii) Thermal cracking If not thermal cracking, CE = 0/2 If blank mark on

1

High temperature Allow ‘high heat’ for ‘high temperature’

(400°C < T < 900°C) or (650 K < T < 1200 K) Not ‘heat’ alone If no T, units must be 650 – 900

and

High pressure (> 10 atm, > 1 MPa, >1000 kPa) 1

(iii) To produce substances which are (more) in demand / produce products with a high value / products worth more

Ignore ‘to make more useful substances’ 1

(d) (i) Corrosive or diagram to show this hazard symbol Ignore irritant, acidic, toxic, harmful

1

(ii) ( 120.5 × 100)(86 + 71 )

=76.75(%) or 76.8(%) Allow answers > 3 sig figs

1

(e) 2,2-dichloro-3–methylpentane Ignore punctuation Any order

1


Page 2

Q1.Vanadium is an important metal. Ferrovanadium, an alloy of iron and vanadium, is used to make a strong type of vanadium-steel. Pure vanadium is used in nuclear reactors.

(a) The table shows some standard enthalpy of formation data.

V2O5(s) CaO(s)

ΔHfθ / kJ mol−1 −1560 −635

In the oldest method of extraction of vanadium, V2O5 is reacted with calcium at a high temperature.

5Ca(s) + V2O5(s) 2V(s) + 5CaO(s)

Use data from the table and the equation to calculate the standard enthalpy change for this reaction.

State the type of reaction that V2O5 has undergone.

Suggest one major reason why this method of extracting vanadium is expensive, other than the cost of heating the reaction mixture.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (5)

(b) Ferrovanadium is produced by the reaction of aluminium with a mixture of V2O5 and iron(III) oxide.

Write an equation for the reaction of aluminium with iron(III) oxide.


Page 3

State the change in oxidation state of aluminium in this reaction.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(c) Pure vanadium, for nuclear reactors, is formed by the reaction of hydrogen with purified VCl2

Write an equation for this reaction in which the only other product is HCl gas.

Identify two hazards in this process, other than the fact that it operates at a high temperature.

Deduce why this process produces pure vanadium, other than the fact that purified VCl2 is used.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (4)

(Total 11 marks)

Q2.(a) Write an equation, including state symbols, for the reaction with enthalpy change equal to the standard enthalpy of formation for CF4(g).

........................................................................................................................ (1)

(b) Explain why CF4 has a bond angle of 109.5°.


Sumayya Baig

Text Box

Energetics

Page 4

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(c) Table 1 gives some values of standard enthalpies of formation (ΔfHϴ).

Table 1

Substance F2(g) CF4(g) HF(g)

ΔfHϴ / kJ mol−1 0 −680 −269

The enthalpy change for the following reaction is −2889 kJ mol−1.

C2H6(g) + 7F2(g) 2CF4(g) + 6HF(g)

Use this value and the standard enthalpies of formation in Table 1 to calculate the standard enthalpy of formation of C2H6(g).

Standard enthalpy of formation of C2H6(g) = .................... kJ mol−1

(3)

(d) Methane reacts violently with fluorine according to the following equation.

CH4(g) + 4F2(g) CF4(g) + 4HF(g) ΔH = −1904 kJ mol−1

Some mean bond enthalpies are given in Table 2.

Table 2

Bond C−H C−F H−F

Mean bond enthalpy / kJ 412 484 562


Page 5

mol−1

A student suggested that one reason for the high reactivity of fluorine is a weak F−F bond.

Is the student correct? Justify your answer with a calculation using these data.

........................................................................................................................

........................................................................................................................ (4)

(Total 10 marks)

Q3.Antimony is a solid element that is used in industry. The method used for the extraction of antimony depends on the grade of the ore.

(a) Antimony can be extracted by reacting scrap iron with low-grade ores that contain antimony sulfide (Sb2S3).

(i) Write an equation for the reaction of iron with antimony sulfide to form antimony and iron(II) sulfide.

............................................................................................................... (1)

(ii) Write a half-equation to show what happens to the iron atoms in this reaction.

............................................................................................................... (1)

(b) In the first stage of the extraction of antimony from a high-grade ore, antimony sulfide is roasted in air to convert it into antimony(III) oxide (Sb2O3) and sulfur dioxide.


............................................................................................................... (1)


Page 6

(ii) Identify one substance that is manufactured directly from the sulfur dioxide formed in this reaction.

............................................................................................................... (1)

(c) In the second stage of the extraction of antimony from a high-grade ore, antimony(III) oxide is reacted with carbon monoxide at high temperature.

(i) Use the standard enthalpies of formation in the table and the equation given below the table to calculate a value for the standard enthalpy change for this reaction.

Sb2O3(s) CO(g) Sb(I) CO2(g)

ΔHf / kJ mol–1 -705 -111 +20 -394

Sb2O3(s) + 3CO(g) 2Sb(I) + 3CO2(g)

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (3)

(ii) Suggest why the value for the standard enthalpy of formation of liquid antimony, given in the table above, is not zero.

...............................................................................................................

............................................................................................................... (1)

(iii) State the type of reaction that antimony(III) oxide has undergone in this reaction.

............................................................................................................... (1)


Page 7

(d) Deduce one reason why the method of extraction of antimony from a low-grade ore, described in part (a), is a low-cost process. Do not include the cost of the ore.

........................................................................................................................

........................................................................................................................ (1)

(Total 10 marks)

Q4.The alcohol 2-methylpropan-2-ol, (CH3)3COH, reacts to form esters that are used as flavourings by the food industry. The alcohol can be oxidised to produce carbon dioxide and water.

A student carried out an experiment on a pure sample of 2-methylpropan-2-ol to determine its enthalpy of combustion. A sample of the alcohol was placed into a spirit burner and positioned under a beaker containing 50 cm3 of water. The spirit burner was ignited and allowed to burn for several minutes before it was extinguished.

The results for the experiment are shown in Table 1.

Table 1

Initial temperature of the water / °C 18.1

Final temperature of the water / °C 45.4

Initial mass of spirit burner and alcohol / g 208.80

Final mass of spirit burner and alcohol / g 208.58

(a) Use the results from Table 1 to calculate a value for the heat energy released from the combustion of this sample of 2-methylpropan-2-ol. The specific heat capacity of water is 4.18 J K–1 g–1. Show your working.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)


Page 2

M1.(a) M1 (could be scored by a correct mathematical expression) M1 ΔH = ΣΔHf (products) − ΣΔHf (reactants) OR a correct cycle of balanced equations

M2 = 5(−635) − (−1560)

= − 3175 + 1560

(This also scores M1)

M3 = − 1615 (kJ mol−1) Award 1 mark ONLY for (+) 1615

Correct answer to the calculation gains all of M1, M2 and M3

Credit 1 mark for(+) 1615 (kJ mol−1) For other incorrect or incomplete answers, proceed as follows • check for an arithmetic error (AE), which is either a transposition error or an incorrect multiplication; this would score 2 marks (M1 and M2) • If no AE, check for a correct method; this requires either a correct cycle with V2O5 and 5CaO OR a clear statement of M1 which could be in words and scores only M1

M4 Type of reaction is • reduction • redox • (or accept) V2O5 / it / V(V) has been reduced

In M4 not “vanadium / V is reduced”

M5 Major reason for expense of extraction − the answer must be about calcium

Calcium is produced / extracted by electrolysis OR calcium is expensive to extract OR calcium extraction uses electricity OR calcium extraction uses large amount of energy OR calcium is a (very) reactive metal / reacts with water or air OR calcium needs to be extracted / does not occur native

QoL

Accept calcium is expensive “to produce” but not “to source, to get, to obtain, to buy” etc. In M5 it is neither enough to say that calcium is “expensive” nor that calcium “must be purified”

5

(b) M1 2Al + Fe2O3 2Fe + Al2O3


Page 3

Ignore state symbols Credit multiples of the equation

M2 (Change in oxidation state) 0 to (+)3 OR (changed by) +3

In M2 if an explanation is given it must be correct and unambiguous

2

(c) M1 VCl2 + H2 V + 2HCl

In M1 credit multiples of the equation

M2 and M3 Two hazards in either order

• HCl / hydrogen chloride / hydrochloric acid is acidic / corrosive / toxic / poisonous

• Explosion risk with hydrogen (gas) OR H2 is flammable For M2 / M3 there must be reference to hydrogen; it is not enough to refer simply to an explosion risk For M2 / M3 with HCl hazard, require reference to acid(ic) / corrosive / toxic only

M4 The only other product / the HCl is easily / readily removed / lost / separated because it is a gas OR will escape (or this idea strongly implied) as a gas OR vanadium / it is the only solid product (and is easily separated) OR vanadium / it is a solid and the other product / HCl is a gas

In M4 it is not enough to state simply that HCl is a gas, since this is in the question.

4

[11]

M2.(a) C(s) + 2F2(g) CF4(g) State symbols essential

1

(b) Around carbon there are 4 bonding pairs of electrons (and no lone pairs) 1

Therefore, these repel equally and spread as far apart as possible


Page 4

1

(c) ΔH = Σ ΔfH products – Σ ΔfH reactants or a correct cycle 1

Hence = (2 × –680) + (6 × –269) – (x) = –2889 1

x = 2889 – 1360 – 1614 = –85 (kJ mol–1) 1

Score 1 mark only for +85 (kJ mol–1)

(d) Bonds broken = 4(C–H) + 4(F–F) = 4 × 412 + 4 × F–F

Bonds formed = 4(C–F) + 4(H–F) = 4 × 484 + 4 × 562 Both required

1

–1904 = [4 × 412 + 4(F–F)] – [4 × 484 + 4 × 562]

4(F–F) = –1904 – 4 × 412 + [4 × 484 + 4 × 562] = 632 1

F–F = 632 / 4 = 158 (kJ mol–1) 1

The student is correct because the F–F bond energy is much less than the C–H or other covalent bonds, therefore the F–F bond is weak / easily broken

Relevant comment comparing to other bonds (Low activation energy needed to break the F–F bond)

1

[10]

M3.(a) (i) 3Fe + Sb2S3 3FeS + 2Sb


Page 5

Or multiples. Ignore state symbols.

1

(ii) Fe Fe2+ + 2e−

Ignore charge on the electron unless incorrect. Or multiples. Credit the electrons being subtracted on the LHS. Ignore state symbols.

1

(b) (i) Sb2S3 + 4.5O2 Sb2O3 + 3SO2

Or multiples. Ignore state symbols.

1

(ii) SO3 or sulfur trioxide / sulfur (VI) oxide Credit also the following ONLY. H2SO4 or sulfuric acid. OR

Gypsum / CaSO4 or plaster of Paris. 1

(c) (i) M1 (could be scored by a correct mathematical expression) Correct answer gains full marks.

M1 ∆Hr = Ʃ∆Hf(products) − Ʃ∆Hf(reactants)

OR a correct cycle of balanced equations / correct numbers of moles Credit 1 mark for +104 (kJ mol−1).

M2 = 2(+20) + 3(−394) − (−705) − 3(−111)

= 40 −1182 + 705 + 333

= −1142 − (−1038)

(This also scores M1)

M3 = −104 (kJ mol−1)

(Award 1 mark ONLY for + 104) For other incorrect or incomplete answers, proceed as follows:


Page 6

• Check for an arithmetic error (AE), which is either a transposition error or an incorrect multiplication; this would score 2 marks. • If no AE, check for a correct method; this requires either a correct cycle with 3CO, 2Sb and 3CO2 OR a clear statement of M1 which could be in words and scores only M1.

3

(ii) It / Sb is not in its standard state

OR

Standard state (for Sb) is solid / (s)

OR

(Sb) liquid is not its standard state Credit a correct definition of standard state as an alternative to the words ‘standard state’. QoL

1

(iii) Reduction OR reduced OR redox 1

(d) Low-grade ore extraction / it

• uses (cheap) scrap / waste iron / steel

• is a single-step process

uses / requires less / low(er) energy Ignore references to temperature / heat or labour or technology.

1

[10]

M4.(a) (Q = mcΔT)

= 50 × 4.18 × 27.3 If incorrect (eg mass = 0.22 or 50.22 g) CE = 0 / 2

1


Page 7

= 5706 J (accept 5700 and 5710) Accept 5.7 kJ with correct unit. Ignore sign.

1

(b) Mr of 2-methylpropan-2-ol = 74(.0) For incorrect Mr, lose M1 but mark on.

1

Moles = mass / Mr

= 0.22 / 74(.0)

= 0.00297 moles 1

ΔH = –5706 / (0.002970 × 1000)

= –1921 (kJ mol–1) If 0.22 is used in part (a), answer = –8.45 kJ mol–1 scores 3

(Allow –1920, –1919) If uses the value given (5580 J), answer = –1879 kJ mol–1 scores 3 Answer without working scores M3 only. Do not penalise precision. Lack of negative sign loses M3

1

(c) ΔH = ΣΔH products – ΣΔH reactants OR a correct cycle

Correct answer with no working scores 1 mark only. 1

ΔH = −(−360) + (4 × −393) + (5 × −286) M2 also implies M1 scored.

1

ΔH = –2642 (kJ mol–1) This answer only.


Page 2

Q1.Which statement about E-1,2-dichloroethene is correct?

A It has the same boiling point as Z-1,2-dichloroethene.

B It forms a polymer with the same repeating unit as Z-1,2-dichloroethene.

C It has the same IR spectrum as Z-1,2-dichloroethene in the range 400–1500 cm−1.

D It has a molecular ion peak different from that of Z-1,2-dichloroethene in its mass spectrum.

(Total 1 mark)

Q2. The table below shows the structures of three isomers with the molecular formula C5H10O

Isomer 1

(E)-pent-3-en-2-ol

Isomer 2

pentanal

Isomer 3

(a) Complete the table by naming Isomer 3. (1)


Page 3

(b) State the type of structural isomerism shown by these three isomers.

..................................................................................................................... (1)

(c) The compound (Z)-pent-3-en-2-ol is a stereoisomer of (E)-pent-3-en-2-ol.

(i) Draw the structure of (Z)-pent-3-en-2-ol.

(1)

(ii) Identify the feature of the double bond in (E)-pent-3-en-2-ol and that in (Z)-pent-3-en-2-ol that causes these two compounds to be stereoisomers.

............................................................................................................. (1)

(d) A chemical test can be used to distinguish between separate samples of Isomer 2 and Isomer 3. Identify a suitable reagent for the test. State what you would observe with Isomer 2 and with Isomer 3.

Test reagent ...............................................................................................

Observation with Isomer 2...........................................................................

.....................................................................................................................

Observation with Isomer 3............................................................................

..................................................................................................................... (3)

(e) The following is the infrared spectrum of one of the isomers 1, 2 or 3.


Sumayya Baig

Text Box

Alkenes

Page 4

(i) Deduce which of the isomers (1, 2 or 3) would give this infrared spectrum. You may find it helpful to refer to Table 1 on the Data Sheet.

............................................................................................................. (1)

(ii) Identify two features of the infrared spectrum that support your deduction. In each case, identify the functional group responsible.

Feature 1 and functional group ...........................................................

.............................................................................................................

.............................................................................................................

.............................................................................................................

Feature 2 and functional group ...........................................................

.............................................................................................................

.............................................................................................................

............................................................................................................. (2)

(Total 10 marks)

Q3. (a) Give the formula of a Group 2 metal hydroxide used in agriculture.

.....................................................................................................................


Page 5

(1)

(b) Identify a sodium halide that does not undergo a redox reaction when added as a solid to concentrated sulfuric acid.

..................................................................................................................... (1)

(c) Chlorine gas reacts with cold dilute sodium hydroxide solution to form sodium chloride and another chlorine-containing compound, X.

Give the formula of X.

..................................................................................................................... (1)

(d) Give the formula of the substance responsible for the orange colour when chlorine gas is bubbled through an aqueous solution of sodium bromide.

..................................................................................................................... (1)

(e) Solid sodium iodide undergoes a redox reaction with concentrated sulfuric acid.

Give the formula for each of the following in this reaction.

Formula of the solid reduction product ......................................................

Formula of the oxidation product ................................................................ (2)

(f) Draw the structure of each of the following organic compounds.

(i) The hydrocarbon that is a chain isomer of methylpropene, but does not exhibit E–Z stereoisomerism.

(1)


Page 6

(ii) The alcohol that is a position isomer of butan-2-ol.

(1)

(iii) The hydrocarbon that has a peak, due to its molecular ion, at m/z = 44 in its mass spectrum.

(1)

(iv) The bromoalkane that reacts with sodium cyanide to produce propanenitrile.

(1)

(Total 10 marks)

Q4.Which statement about ethene is correct?

A It has no geometric isomers because there is free rotation around the C=C bond.

B It reacts with HBr in a nucleophilic addition reaction.


Page 7

C It burns in excess oxygen to produce carbon dioxide and water.

D The C=C bond is twice as strong as the C–C bond in ethane.

(Total 1 mark)

Q5.It is possible to convert but-1-ene into its structural isomer but-2-ene.

(a) State the type of structural isomerism shown by but-1-ene and but-2-ene.

........................................................................................................................ (1)

(b) The first stage in this conversion involves the reaction of hydrogen bromide with but-1-ene.

CH3CH2CH=CH2 + HBr CH3CH2CHBrCH3

Outline a mechanism for this reaction.

(4)

(c) The second stage is to convert 2-bromobutane into but-2-ene.

CH3CH2CHBrCHCH3

+ KOH CH3CH=CHCH3 + KBr + H2O

Outline a mechanism for this reaction.


Page 2

M1.B [1]

M2. (a) Pentan-2-one ONLY but ignore absence of hyphens

1

(b) Functional group (isomerism) Both words needed

1

(c) (i)

Award credit provided it is obvious that the candidate is drawing the Z / cis isomer The group needs to be CHOHCH3 but do not penalise poor C–C bonds or absence of brackets around OH Trigonal planar structure not essential

1

(ii) Restricted rotation (about the C=C)

OR

No (free) rotation (about the C=C) 1

(d)

M1 Tollens’ (reagent)

(Credit ammoniacal silver nitrate OR a description of making Tollens’)

(Do not credit Ag+, AgNO3 or [Ag(NH3)2

+] or “the silver mirror test”

M1 Fehling’s (solution) / Benedict’s

(Penalise Cu2+(aq) or CuSO4 but mark M2 and M3)


Page 3

on their own, but mark M2 and M3)

M2 silver mirror

OR black solid or black precipitate

M2 Red solid/precipitate

(Credit orange or brown solid)

M3 (stays) colourless

OR

no (observed) change / no reaction

M3 (stays) blue

OR

no (observed) change / no reaction

If M1 is blank CE = 0, for the clip Check the partial reagents listed and if M1 has a totally incorrect reagent, CE = 0 for the clip Allow the following alternatives M1 (acidified) potassium dichromate(VI) (solution); mark on from incomplete formulae or incorrect oxidation state M2 (turns) green M3 (stays) orange / no (observed) change / no reaction OR M1 (acidified) potassium manganate(VII) (solution); mark on from incomplete formulae or incorrect oxidation state M2 (turns) colourless M3 (stays) purple / no (observed) change / no reaction In all cases for M3 Ignore “nothing (happens)” Ignore “no observation”

3

(e) (i) Spectrum is for Isomer 1

or named or correctly identified The explanation marks in (e)(ii) depend on correctly identifying Isomer 1. The identification should be unambiguous but candidates should not be penalised for an imperfect or incomplete name. They may say “the alcohol” or the “alkene” or the “E isomer”

1

(ii) If Isomer 1 is correctly identified, award any two from

• (Strong / broad) absorption / peak in the range


Page 4

3230 to 3550 cm–1 or specified value in this range or marked correctly on spectrum and (characteristic absorption / peak for) OH group /alcohol group

• No absorption / peak in range 1680 to 1750 cm–1 or absence marked correctly on spectrum and (No absorption / peak for a) C=O group / carbonyl group / carbon-oxygen double bond

• Absorption / peak in the range 1620 to 1680 cm–1

or specified value in this range or marked correctly on spectrum and

(characteristic absorption / peak for) C=C group / alkene / carbon-carbon double bond

If 6(e)(i) is incorrect or blank, CE=0 Allow the words “dip” OR “spike” OR “trough” OR “low transmittance” as alternatives for absorption. Ignore reference to other absorptions e.g. C-H, C-O

2

[10]

M3. (a) Ca(OH)2 OR Mg(OH)2

Ignore name Could be ionic

1

(b) NaF or sodium fluoride

OR

NaCl or sodium chloride Either formula or name can score Do not penalise the spelling “fluoride” When both formula and name are written, • penalise contradictions • if the attempt at the correct formula is incorrect, ignore it and credit correct name for the mark unless contradictory


Page 5

• if the attempt at the correct name is incorrect, ignore it and credit correct formula for the mark unless contradictory

1

(c) NaClO OR NaOCl Ignore name (even when incorrect) The correct formula must be clearly identified if an equation is written

1

(d) Br2 (ONLY) Only the correct formula scores; penalise lower case “b”, penalise upper case “R”, penalise superscript Ignore name The correct formula must be clearly identified if an equation is written

1

(e) M1 S OR S8 OR S2

M2 I2 (ONLY) Ignore names penalise lower case “i” for iodine, penalise superscripted numbers Mark independently The correct formula must be clearly identified in each case if an equation is written

2

(f) (i) CH3CH2CH=CH2

Structure of but-1-ene. Ignore name Credit “sticks” for C-H bonds

1

(ii) CH3CH2CH2CH2OH Structure of butan-1-ol. Ignore name Credit “sticks” for C-H bonds

1


Page 6

(iii) CH3CH2CH3

Structure of propane. Ignore name Ignore calculations and molecular formula Credit “sticks” for C-H bonds Ignore the molecular ion

1

(iv) CH3CH2Br OR C2H5Br

Structure of bromoethane. Ignore name and structure of nitrile Credit “sticks” for C-H bonds

1

[10]

M4.C [1]

M5.(a) Position(al) (isomerism) 1

(b) Penalise one mark from their total if half-headed arrows are used

M1 must show an arrow from the double bond towards the H atom of the H–Br molecule

M1 Ignore partial negative charge on the double bond.


Page 7

M2 must show the breaking of the H–Br bond. M2 Penalise partial charges on H–Br bond if wrong way and penalise formal charges

M3 is for the structure of the secondary carbocation. Penalise M3 if there is a bond drawn to the positive charge

M4 must show an arrow from the lone pair of electrons on the negatively charged bromide ion towards the positively charged carbon atom of either a primary or secondary carbocation.

Penalise once only in any part of the mechanism for a line and two dots to show a bond Maximum any 3 of 4 marks for wrong reactant or primary carbocation. If Br2 is used, maximum 2 marks for their mechanism Do not penalise the use of “sticks”

NB The arrows here are double-headed 4

(c)

Penalise one mark from their total if half-headed arrows are used

M1 must show an arrow from the lone pair on oxygen of a negatively charged hydroxide ion to a correct H atom

Penalise M1 if covalent KOH

M2 must show an arrow from a C–H bond adjacent to the C–Br bond towards the appropriate C–C bond. Only award if an arrow is shown attacking the H atom of an adjacent C–H (in M1)

M3 is independent provided it is from their original molecule. Penalise M3 for formal charge on C of the C–Br or incorrect partial charges on C–Br Penalise M3 if an extra arrow is drawn from the Br of the C–Br bond to, for example, K+

Ignore other partial charges Penalise once only in any part of the mechanism for a line and two dots to show a bond. Maximum any 2 of 3 marks for wrong reactant or wrong product(if shown) or a mechanism that leads to but-1-ene


Page 2

Q1.This question is about the elements in Period 3 of the Periodic Table.

(a) State the element in Period 3 that has the highest melting point. Explain your answer.

Element ..........................................................................................................

Explanation ....................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (3)

(b) State the element in Period 3 that has the highest first ionisation energy. Explain your answer.

Element ..........................................................................................................

Explanation ....................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (3)

(c) Suggest the element in Period 3 that has the highest electronegativity value.

........................................................................................................................ (1)

(d) Chlorine is a Period 3 element. Chlorine forms the molecules ClF3 and CCl2

(i) Use your understanding of electron pair repulsion to draw the shape of ClF3 and the shape of CCl2

Include any lone pairs of electrons that influence the shape.


Page 3

Shape of ClF3 Shape of CCl2 (2)

(ii) Name the shape of CCl2

............................................................................................................... (1)

(iii) Write an equation to show the formation of one mole of ClF3 from its elements.

............................................................................................................... (1)

(Total 11 marks)

Q2.Aluminium and thallium are elements in Group 3 of the Periodic Table. Both elements form compounds and ions containing chlorine and bromine.

(a) Write an equation for the formation of aluminium chloride from its elements.

........................................................................................................................ (1)

(b) An aluminium chloride molecule reacts with a chloride ion to form the AlCl4− ion.

Name the type of bond formed in this reaction. Explain how this type of bond is formed in the AlCl4

− ion.

Type of bond ..................................................................................................

Explanation ....................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(c) Aluminium chloride has a relative molecular mass of 267 in the gas phase.

Deduce the formula of the aluminium compound that has a relative molecular mass of 267


Sumayya Baig

Text Box

Bonding

Page 4

........................................................................................................................ (1)

(d) Deduce the name or formula of a compound that has the same number of atoms, the same number of electrons and the same shape as the AlCl4

− ion.

........................................................................................................................ (1)

(e) Draw and name the shape of the TlBr52− ion.

Shape of the TlBr52− ion.

Name of shape .............................................................................................. (2)

(f) (i) Draw the shape of the TlCl2+ ion.

(1)

(ii) Explain why the TlCl2+ ion has the shape that you have drawn in part (f)(i).

........................................................................................................................

........................................................................................................................

........................................................................................................................ (1)

(g) Which one of the first, second or third ionisations of thallium produces an ion with the electron configuration [Xe] 5d106s1?

Tick ( ) one box.


Page 5

First

Second

Third

(1)

(Total 10 marks)

Q3.Thallium is in Group 3 of the Periodic Table. Thallium reacts with halogens to form many compounds and ions.

(a) Draw the shape of the TlBr32– ion and the shape of the TlCl4

3– ion. Include any lone pairs of electrons that influence the shapes.

Name the shape made by the atoms in TlBr32– and suggest a value for the bond

angle.

........................................................................................................................ (4)

(b) Thallium(I) bromide (TlBr) is a crystalline solid with a melting point of 480 °C.

Suggest the type of bonding present in thallium(I) bromide and state why the melting point is high.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................


Page 6

........................................................................................................................

........................................................................................................................ (3)

(c) Write an equation to show the formation of thallium(I) bromide from its elements.

........................................................................................................................ (1)

(Total 8 marks)

Q4.A hydrogen peroxide molecule can be represented by the structure shown.

(a) Suggest a value for the H−O−O bond angle.

........................................................................................................................ (1)

(b) Hydrogen peroxide dissolves in water.

(i) State the strongest type of interaction that occurs between molecules of hydrogen peroxide and water.

............................................................................................................... (1)

(ii) Draw a diagram to show how one molecule of hydrogen peroxide interacts with one molecule of water. Include all lone pairs and partial charges in your diagram.


Page 7

(3)

(c) Explain, in terms of electronegativity, why the boiling point of H2S2 is lower than H2O2.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(Total 7 marks)

Q5.(a) Write an equation, including state symbols, for the reaction with enthalpy change equal to the standard enthalpy of formation for CF4(g).

........................................................................................................................ (1)

(b) Explain why CF4 has a bond angle of 109.5°.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................


Page 2

M1.(a) Silicon / Si If not silicon then CE = 0 / 3

1

covalent (bonds) M3 dependent on correct M2

1

Strong or many of the (covalent) bonds need to be broken / needs a lot of energy to break the (covalent) bonds

Ignore hard to break 1

(b) Argon / Ar If not argon then CE = 0 / 3. But if Kr chosen, lose M1 and allow M2+M3

1

Large(st) number of protons / large(st) nuclear charge Ignore smallest atomic radius

1

Same amount of shielding / same number of shells / same number of energy levels

Allow similar shielding 1

(c) Chlorine / Cl Not Cl2, Not CL, Not Cl2

1

(d) (i)

Or any structure with 3 bonds and 2 lone pairs Ignore any angles shown

1


Page 3

Or a structure with 2 bonds and 1 lone pair

1

(ii) Bent / v shape Ignore non-linear, angular and triangular Apply list principle

1

(iii) Cl2 + F2 ClF3

No multiples Ignore state symbols

1 [11]

M2.(a) Al + 1.5Cl 2 → AlCl3

Accept multiples. Also 2Al + 3Cl2 → Al2Cl6

Ignore state symbols. 1

(b) Coordinate / dative (covalent) If wrong CE=0/2 if covalent mark on.

1

Electron pair on Cl − donated to Al(Cl 3) QoL Lone pair from Cl − not just Cl Penalise wrong species.

1

(c) Al2Cl6 or AlBr3

Allow Br3Al or Cl6Al2

Upper and lower case letters must be as shown. Not 2AlCl3

1


Page 4

(d) SiCl4 / silicon tetrachloride Accept silicon(4) chloride or silicon(IV) chloride. Upper and lower case letters must be as shown. Not silicon chloride.

1

(e)

Accept shape containing 5 bonds and no lone pairs from Tl to each of 5 Br atoms. Ignore charge.

1

Trigonal bipyramid(al) 1

(f) (i) Cl — Tl — Cl

Accept this linear structure only with no lone pair on Tl 1

(ii) (Two) bonds (pairs of electrons) repel equally / (electrons in) the bonds repel to be as far apart as possible

Dependent on linear structure in (f)(i). Do not allow electrons / electron pairs repel alone.

1

(g) Second 1

[10]


Page 5

M3.(a)

Mark is for correct number of bonds and lone pair in each case. Ignore charges if shown.

2

Pyramidal / trigonal pyramid Allow tetrahedral.

1

107° Allow 107 to 107.5°.

1

(b) M1 Ionic CE = 0 / 3 if not ionic.

1

M2 Oppositely charged ions / Tl+ and Br− ions If molecules / intermolecular forces / metallic bonding, CE=0.

1

M3 Strong attraction between ions M3 dependent on M2. Allow ‘needs a lot of energy to break / overcome’ instead of ‘strong’.

1

(c) Tl + TlBr Allow multiples.


Page 6

Ignore state symbols even if incorrect. 1

[8]

M4.(a) 94−105.5° 1

(b) (i) Hydrogen bond(ing) / H bonding / H bonds Not just hydrogen

1

(ii)

OR

1 mark for all lone pairs 1 mark for partial charges on the O and the H that are involved in H bonding 1 mark for the H-bond, from Hδ+ on one molecule to lone pair on O of other molecule

3

(c) Electronegativity of S lower than O or electronegativity difference between H and S is lower


Page 7

Mark independently 1

No hydrogen bonding between H2S2 molecules

Or only van der Waals / only dipole-dipole forces between H2S2 molecules If breaking covalent bonds CE = 0

1 [7]

M5.(a) C(s) + 2F2(g) CF4(g) State symbols essential

1

(b) Around carbon there are 4 bonding pairs of electrons (and no lone pairs) 1

Therefore, these repel equally and spread as far apart as possible 1

(c) ΔH = Σ ΔfH products – Σ ΔfH reactants or a correct cycle 1

Hence = (2 × –680) + (6 × –269) – (x) = –2889 1

x = 2889 – 1360 – 1614 = –85 (kJ mol–1) 1

Score 1 mark only for +85 (kJ mol–1)

(d) Bonds broken = 4(C–H) + 4(F–F) = 4 × 412 + 4 × F–F

Bonds formed = 4(C–F) + 4(H–F) = 4 × 484 + 4 × 562 Both required


Page 2

Q1. The following table gives the melting points of some elements in Period 3.

Element Na Al Si P S

Melting point / K 371 933 1680 317 392

(a) State the type of structure shown by a crystal of silicon. Explain why the melting point of silicon is very high.

......................................................................................................................

......................................................................................................................

......................................................................................................................

......................................................................................................................

...................................................................................................................... (3)

(b) State the type of structure shown by crystals of sulfur and phosphorus. Explain why the melting point of sulfur is higher than the melting point of phosphorus.

......................................................................................................................

......................................................................................................................

......................................................................................................................

......................................................................................................................

...................................................................................................................... (3)

(c) Draw a diagram to show how the particles are arranged in aluminium and explain why aluminium is malleable. (You should show a minimum of six aluminium particles arranged in two dimensions.)

......................................................................................................................

......................................................................................................................

......................................................................................................................

......................................................................................................................


Page 3

......................................................................................................................

...................................................................................................................... (3)

(d) Explain why the melting point of aluminium is higher than the melting point of sodium.

......................................................................................................................

......................................................................................................................

......................................................................................................................

......................................................................................................................

......................................................................................................................

...................................................................................................................... (3)

(Total 12 marks)

Q2. The following diagram shows the first ionisation energies of some Period 3 elements.

(a) Draw a cross on the diagram to show the first ionisation energy of aluminium. (1)

(b) Write an equation to show the process that occurs when the first ionisation energy of aluminium is measured.


Sumayya Baig

Text Box

Periodicity

Page 4

...................................................................................................................... (2)

(c) State which of the first, second or third ionisations of aluminium would produce an ion with the electron configuration 1s2 2s2 2p6 3s1

...................................................................................................................... (1)

(d) Explain why the value of the first ionisation energy of sulfur is less than the value of the first ionisation energy of phosphorus.

......................................................................................................................

......................................................................................................................

......................................................................................................................

...................................................................................................................... (2)

(e) Identify the element in Period 2 that has the highest first ionisation energy and give its electron configuration.

Element .......................................................................................................

Electron configuration .................................................................................. (2)

(f) State the trend in first ionisation energies in Group 2 from beryllium to barium. Explain your answer in terms of a suitable model of atomic structure.

Trend …........................................................................................................

Explanation ..................................................................................................

......................................................................................................................

......................................................................................................................

...................................................................................................................... (3)

(Total 11 marks)


Page 5

Q3. Ionisation energies provide evidence for the arrangement of electrons in atoms.

(a) Complete the electron configuration of the Mg+ ion.

1s2 ................................................................................................................ (1)

(b) (i) State the meaning of the term first ionisation energy.

.............................................................................................................

.............................................................................................................

............................................................................................................. (2)

(ii) Write an equation, including state symbols, to show the reaction that occurs when the second ionisation energy of magnesium is measured.

............................................................................................................. (1)

(iii) Explain why the second ionisation energy of magnesium is greater than the first ionisation energy of magnesium.

.............................................................................................................

.............................................................................................................

............................................................................................................. (1)

(iv) Use your understanding of electron arrangement to complete the table by suggesting a value for the third ionisation energy of magnesium.

First Second Third Fourth Fifth


Page 6

Ionisation energies of magnesium / kJ mol–1 736 1450 10 500 13 629

(1)

(c) State and explain the general trend in the first ionisation energies of the Period 3 elements sodium to chlorine.

Trend ...........................................................................................................

Explanation ..................................................................................................

......................................................................................................................

...................................................................................................................... (3)

(d) State how the element sulfur deviates from the general trend in first ionisation energies across Period 3. Explain your answer.

How sulfur deviates from the trend ..............................................................

......................................................................................................................

Explanation ..................................................................................................

......................................................................................................................

...................................................................................................................... (3)

(e) A general trend exists in the first ionisation energies of the Period 2 elements lithium to fluorine. Identify one element which deviates from this general trend.

...................................................................................................................... (1)

(Total 13 marks)

Q4. (a) Complete the electronic configuration for the sodium ion, Na+


Page 7

ls2 ................................................................................................................. (1)

(b) (i) Write an equation, including state symbols, to represent the process for which the energy change is the second ionisation energy of sodium.

............................................................................................................. (2)

(ii) Explain why the second ionisation energy of sodium is greater than the second ionisation energy of magnesium.

.............................................................................................................

.............................................................................................................

.............................................................................................................

............................................................................................................. (3)

(iii) An element X in Period 3 of the Periodic Table has the following successive ionisation energies.

First Second Third Fourth

Ionisation energies / kJ mol–1 577 1820 2740 11600

Deduce the identity of element X.

............................................................................................................. (1)

(c) State and explain the trend in atomic radius of the Period 3 elements from sodium to chlorine.

Trend ...........................................................................................................

Explanation ..................................................................................................

......................................................................................................................

...................................................................................................................... (3)


Page 2

M1. (a) Macromolecular/giant covalent/giant molecular/giant atomic If IMF/H-bonds/Ionic/metallic CE = 0/3 covalent bond between molecules CE = 0/3 If giant unqualified M1 = 0 but mark on

1

Many/strong covalent bonds M2 and M3 can only be scored if covalent mentioned in answer Ignore metalloid and carbon Ignore bp

1

Bonds must be broken/overcome Ignore numbers of bonds and references to energy

1

(b) (Simple) molecular QoL Do not allow simple covalent for M1 Giant covalent/ionic/metallic, CE = 0 If breaking covalent bonds CE= 0/3

1

S bigger molecule (than P) or S8 and P4 references QoL Allow more electrons in sulfur molecule or S8

Do not allow S is bigger then P Allow S molecule has a bigger Mr

Do not allow contradictions 1

So more/stronger van der Waals’ forces (to be broken or overcome) Not just more energy to break

1

(c) Regular arrangement of minimum of 6 particles in minimum of 2 rows

Ignore e– Do not allow ring arrangements OR structures bonded with electrons

1

+ charge in each one (of 6)


Page 3

Allow +, (1+, 2+ or 3+) in ions/or in words 1

Rows/planes/sheets/layers (of atoms/ions) can slide (owtte) over one another

M3 independent If ionic bonding/molecules/IMF/vdw/covalent, penalise M3 Ignore layers of electrons sliding

1

(d) Bigger charge (3+ compared to 1+) CE = 0 if molecules, ionic, covalent, IMF (Allow Al2+)

OR smaller atom/ion in Al/more protons/bigger nuclear charge 1

More free/delocalised electrons (in Al)/bigger sea of electrons in Al Accept 2 or 3 delocalised electrons compared to 1 in Na

1

Stronger metallic bonding/stronger (electrostatic) attraction between the (+) ions or nuclei and the (delocalised) electrons (or implied)

Must be implied that the electrons are the delocalised ones not the electrons in the shells. Accept converse arguments

1

[12]

M2. (a) Cross between the Na cross and the Mg cross 1

(b) Al(g) → Al+(g) + e– Al(g) – e– → Al+(g) Al(g) + e– → Al+(g) + 2e–

One mark for state symbols consequential on getting equation correct. Electron does not have to have the – sign on it Ignore (g) if put as state symbol with e– but penalise state symbol mark if other state symbols on e–


Page 4

2

(c) 2nd/second/2/II Only

1

(d) Paired electrons in (3)p orbital Penalise wrong number If paired electrons repel allow M2

1

repel 1

(e) Neon/Ne No consequential marking from wrong element

1

1s22s22p6/[He}2s22p6

Allow capital s and p Allow subscript numbers

1

(f) Decreases CE if wrong

1

Atomic radius increases/electron removed further from nucleus or nuclear charge/electron in higher energy level/Atoms get larger/more shells

Accept more repulsion between more electrons for M2 Mark is for distance from nucleus Must be comparative answers from M2 and M3 CE M2 and M3 if mention molecules Not more sub-shells

1

As group is descended more shielding 1

[11]


Page 5

M3. (a) 2s22p63s1

1s2 can be rewritten Allow 2s22px

22py22pz

23s1

Allow subscripts and capitals 1

(b) (i) Energy/enthalpy (needed) to remove one mole of electrons from one mole of atoms/compounds/molecules/elements

1

OR

Energy to form one mole of positive ions from one mole of atoms

OR

Energy/enthalpy to remove one electron from one atom

In the gaseous state (to form 1 mol of gaseous ions) Energy given out loses M1 M2 is dependent on a reasonable attempt at M1 Energy needed for this change X(g) → X+(g) + e(–) = 2 marks This equation alone scores one mark

1

(ii) Mg+(g) → Mg2+(g) + e(–)

Mg+(g) + e(–) → Mg2+(g) + 2e(–)

Mg+(g) – e(–) → Mg2+(g) Do not penalise MG Not equation with X

1

(iii) Electron being removed from a positive ion (therefore need more energy)/electron being removed is closer to the nucleus/Mg+

smaller (than Mg)/Mg+ more positive than Mg Allow from a + particle/species Not electron from a higher energy level/or higher sub-level More protons = 0

1

(iv) Range from 5000 to 9000 kJ mol–1

1


Page 6

(c) Increase If decrease CE = 0/3 If blank mark on

1

Bigger nuclear charge (from Na to Cl)/more protons QWC

1

electron (taken) from same (sub)shell/similar or same shielding/ electron closer to the nucleus/smaller atomic radius

If no shielding = 0 Smaller ionic radius = 0

1

(d) Lower If not lower CE = 0/3 If blank mark on Allow does not increase

1

Two/pair of electrons in (3)p orbital or implied Not 2p

1

repel (each other) M3 dependent upon a reasonable attempt at M2

1

(e) Boron/B or oxygen/O/O2

1

[13]

M4. (a) 2s2 2p6; If ignored the 1s2 given and written 1s22s22p6 mark as correct Allow capitals and subscripts

1


Page 7

(b) (i) Na+(g) → Na2+ (g) + e(–); One mark for equation and one mark for state symbols

Na+(g) + e(–) → Na2+ (g) + 2e(–); M2 dependent on M1 Allow Na+(g) – e(–) → Na(g) Allow X+(g) → X2+ (g) + e = 1 mark

2

(ii) Na(2+) requires loss of e– from a 2(p) orbital or 2nd energy level or 2nd shell and Mg(2+) requires loss of e– from a 3(s) orbital or 3rd

energy level or 3rd shell / Na(2+) loses e from a lower (energy) orbital/ or vice versa;

Not from 3p 1

Less shielding (in Na); Or vice versa for Mg

1

e(–) closer to nucleus/ more attraction (of electron to nucleus) (in Na); M3 needs to be comparative

1

(iii) Aluminium /Al; 1

(c) Decreases; If not decreases CE = 0 If blank, mark on

1

Increasing nuclear charge/ increasing number of protons; 1

Electrons in same shell or level/ same shielding/ similar shielding; 1

(d) Answer refers to Na; Allow converse answers relating to Mg.

Na fewer protons/smaller nuclear charge/ fewer delocalised electrons; Allow Mg is 2+ and Na is +. If vdw CE = 0.


Page 2

Q1.The table below shows observations of changes from some test-tube reactions of aqueous solutions of compounds Q, R and S with five different aqueous reagents. The initial colours of the solutions are not given.

BaCl2 +

HCl AgNO3 +

HNO3

NaOH Na2CO3 HCl (conc)

Q no change observed

pale cream precipitate

white precipitate

white precipitate

no change observed

R no change observd

white precipitate

white precipitate, dissolves in excess of

NaOH

white precipitate,

bubbles of a gas

no change observed

S white

precipitate no change observed

brown precipitate

brown precipitate,

bubbles of a gas

yellow solution

(a) Identify each of compounds Q, R and S. You are not required to explain your answers.

Identity of Q ...................................................................................................

........................................................................................................................

Identity of R ....................................................................................................

........................................................................................................................

Identity of S ....................................................................................................

........................................................................................................................ (6)

(b) Write ionic equations for each of the positive observations with S.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................


Page 3

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (4)

(Total 10 marks)

Q2.There are many uses for Group 2 metals and their compounds.

(a) State a medical use of barium sulfate. State why this use of barium sulfate is safe, given that solutions containing barium ions are poisonous.

Use .................................................................................................................

Why this use is safe ........................................................................................

........................................................................................................................

........................................................................................................................ (2)

(b) Magnesium hydroxide is used in antacid preparations to neutralise excess stomach acid.

Write an equation for the reaction of magnesium hydroxide with hydrochloric acid.

........................................................................................................................ (1)

(c) Solutions of barium hydroxide are used in the titration of weak acids.

State why magnesium hydroxide solution could not be used for this purpose.

........................................................................................................................

........................................................................................................................ (1)


Sumayya Baig

Text Box

Group 2

Page 4

(d) Magnesium metal is used to make titanium from titanium(IV) chloride.

Write an equation for this reaction of magnesium with titanium(IV) chloride.

........................................................................................................................ (1)

(e) Magnesium burns with a bright white light and is used in flares and fireworks.

Use your knowledge of the reactions of Group 2 metals with water to explain why water should not be used to put out a fire in which magnesium metal is burning.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

(Extra space) ................................................................................................

........................................................................................................................ (2)

(Total 7 marks)

Q3.A student investigated how the initial rate of reaction between sulfuric acid and magnesium at 20 °C is affected by the concentration of the acid.

The equation for the reaction is

H2SO4(aq) + Mg(s) MgSO4(aq) + H2(g)

(a) The student made measurements every 20 seconds for 5 minutes. The student then repeated the experiment using double the concentration of sulfuric acid.

State a measurement that the student should make every 20 seconds. Identify the apparatus that the student could use to make this measurement.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)


Page 5

(b) State one condition, other than temperature and pressure, that would need to be kept constant in this investigation.

...........................................................................................................................

........................................................................................................................... (1)

(c) When the student had finished the investigation, an excess of sodium hydroxide solution was added to the reaction mixture. This was to neutralise any unreacted sulfuric acid. The student found that a further reaction took place, producing magnesium hydroxide.

(i) Draw a diagram to show how the student could separate the magnesium hydroxide from the reaction mixture.

(2)

(ii) Suggest one method the student could use for removing soluble impurities from the sample of magnesium hydroxide that has been separated.

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (1)

(Total 6 marks)

Q4.(a) Anhydrous strontium chloride is not used in toothpaste because it absorbs water from the atmosphere. The hexahydrate, SrCl2.6H2O, is preferred.


Page 6

A chemist was asked to determine the purity of a sample of strontium chloride hexahydrate. The chemist weighed out 2.25 g of the sample and added it to 100 cm3 of water. The mixture was warmed and stirred for several minutes to dissolve all of the strontium chloride in the sample. The mixture was then filtered into a conical flask. An excess of silver nitrate solution was added to the flask and the contents swirled for 1 minute to make sure that the precipitation was complete.

The silver chloride precipitate was separated from the mixture by filtration. The precipitate was washed several times with deionised water and dried carefully. The chemist weighed the dry precipitate and recorded a mass of 1.55 g.

(i) Calculate the amount, in moles, of AgCl in 1.55 g of silver chloride (Mr = 143.4).

............................................................................................................... (1)

(ii) The equation for the reaction between strontium chloride and silver nitrate is

SrCl2 + 2AgNO3 2AgCl + Sr(NO3)2

Use your answer from part (i) and this equation to calculate the amount, in moles, of SrCl2 needed to form 1.55 g of silver chloride.

...............................................................................................................

............................................................................................................... (1)

(iii) Use data from the Periodic Table to calculate the Mr of strontium chloride hexahydrate. Give your answer to 1 decimal place.

...............................................................................................................

............................................................................................................... (1)

(iv) Use your answers from parts (a)(ii) and (a)(iii) to calculate the percentage by mass of strontium chloride hexahydrate in the sample. Show your working. Give your answer to the appropriate precision.

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (2)


Page 7

(v) Several steps in the practical procedure were designed to ensure an accurate value for the percentage by mass of strontium chloride hexahydrate in the sample.

1 Explain why the solution of strontium chloride was filtered to remove insoluble impurities before the addition of silver nitrate.

.........................................................................................................

......................................................................................................... (1)

2 Explain why the precipitate of silver chloride was washed several times with deionised water.

.........................................................................................................

......................................................................................................... (1)

(b) Magnesium hydroxide and magnesium carbonate are used to reduce acidity in the stomach. Magnesium hydroxide can be prepared by the reaction of solutions of magnesium chloride and sodium hydroxide.

(i) Write the simplest ionic equation for the reaction that occurs between magnesium chloride and sodium hydroxide. Include state symbols in your equation.

............................................................................................................... (1)

(ii) Other than cost, explain one advantage of using magnesium hydroxide rather than magnesium carbonate to reduce acidity in the stomach.

...............................................................................................................

............................................................................................................... (1)

(c) Calcium ethanoate, (CH3COO)2Ca, is used in the treatment of kidney disease. Thermal decomposition of calcium ethanoate under certain conditions gives propanone and one other product.


Page 2

M1.(a) Q is calcium or magnesium 1

bromide 1

R is aluminium 1

chloride 1

S is iron(III) 1

sulfate 1

Mark this question independently

(b) Ba2+ + SO42– BaSO4

1

[Fe(H2O)6]3+ + 3OH– Fe(H2O)3(OH)3 + 3H2O 1

2[Fe(H2O)6]3+ + 3CO32– 2Fe(H2O)3(OH)3 + 3H2O + 3CO2

1

[Fe(H2O)6]3+ + 4Cl– [FeCl4]– + 6H2O 1


Page 3

[10]

M2.(a) M1 Used in a barium meal / barium swallow / barium enema

OR (used to absorb) X-rays Credit a correct reference to M1 written in the explanation in M2 unless contradictory.

M2 BaSO4 / barium sulfate / it is insoluble For M2 penalise obvious reference to barium or to barium ions being insoluble.

2

(b) Mg(OH)2 + 2HCl MgCl2 + 2H2O Or multiples. Ignore state symbols.

1

(c) It / magnesium hydroxide is insoluble / insufficiently soluble / sparingly soluble / less soluble than barium hydroxide / forms low concentration solutions

Weak alkali alone is insufficient. Formation of a precipitate needs explanation.

1

(d) TiCl4 + 2Mg 2MgCl2 + Ti Or multiples. Ignore state symbols.

1

(e) M1 Hydrogen / H2 produced

OR an equation to produce hydrogen / H2

( eg Mg + 2H2O Mg(OH)2 + H2)

( eg Mg + H2O MgO + H2) For M1

Do not penalise an incorrect equation; the mark is for H2 or hydrogen. Award one mark only for ‘exothermic reaction with steam /


Page 4

H2O’ for a student who has not scored M1

M2 requires correct M1

risk of explosion

OR forms explosive mixture (with air)

OR (highly) flammable Ignore ‘violent’ reaction.

2

[7]

M3.(a) (Measure the) volume of gas / mass of the container + contents 1

Suitable named piece of equipment Gas syringe (or inverted burette or measuring cylinder, as long as student has referred to the cylinder being filled with water) / balance. Equipment must be correct for the measurement stated.

1

(b) Any one of:

• Mass of magnesium Allow amount of magnesium.

• Surface area of magnesium 1

(c) (i) Gravity: Conical flask or beaker and funnel /

Vacuum: Sealed container with a side arm and Buchner or Hirsch funnel Must be either gravity filtration (with a V-shaped funnel) or vacuum filtration (with a side-arm conical flask) appropriately drawn.

1

Filter paper Must show filter paper as at least two sides of a triangle


Page 5

(V-shaped) for gravity filtration or horizontal filter paper for vacuum filtration.

1

(ii) Wash with / add (a small amount of cold) water Ignore filtering.

1

[6]

M4.(a) (i) 1.08 × 10–2

Do not penalise precision but must be to at least 2 significant figures. Do not accept 1 × 10–2

1

(ii) 5.4(0) × 10–3

Allow (i) / 2 Do not penalise precision but must be to at least 2 significant figures.

1

(iii) 266.6 Lose this mark if answer not given to 1 decimal place.

1

(iv) mass = 5.4(0) × 10–3 × 266.6 = 1.44 g M1

Allow (ii) × (iii). 1

percentage = 1.44 × 100 / 2.25 = 64.0 M2

Allow consequential answer from M1

Lose this mark if answer not given to 3 significant figures. Correct answer with no working scores M2 only.

1

(v) 1 Would give an incorrect / too large mass (of silver chloride)


Page 6

Do not allow ‘to get an accurate result’ without qualification. 1

2 To remove soluble impurities / excess silver nitrate (solution) / strontium nitrate (solution) Do not allow ‘to remove impurities’. Do not allow ‘to remove excess strontium chloride solution’.

1

(b) (i) Mg2+(aq) + 2OH-(aq) → Mg(OH)2(s) Allow Mg2+(aq) + 2OH-(aq) → Mg2+(OH-)2(s) Allow multiples, including fractions. Lose mark if state symbols are missing or incorrect. Lose mark if incorrect charge on an ion.

1

(ii) Does not produce CO2 / gas which distends stomach / does not produce wind / does not increase pressure in stomach

Allow ‘prevents flatulence’ and ‘prevents burping’. Do not allow ‘gas’ without qualification.

1

(c) (CH3COO)2Ca → CH3COCH3 + CaCO3

Allow multiples. Allow propanone as C3H6O Allow (CH3COO-)2Ca2+ → CH3COCH3 + Ca2+CO3

2-

1

(d) Ca (salt) - no visible change with sodium chromate(VI) M1

Allow ‘yellow solution formed’ or ‘no ppt. forms’. Allow M1 and M2 in any order.

1

Sr and Ba (salts) give (yellow) precipitate with sodium chromate(VI) M2

Lose this mark if precipitate has an incorrect colour. 1


Ark Globe Academy - Chemistry Year 12 12... · 2020. 4. 20. · Chemistry Year 12 School Closure Pack A timetable has been created for you to ensure that your work is manageable.

Documents