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ST ANDREWS JUNIOR COLLEGE
JC1 Final Examination
Chemistry
Higher 2
9647
4 Oct 2010
2 hours
Candidates answer on separate paper.
Additional Materials: Multiple choice answer sheet, Writing
paper, Data Booklet
READ THESE INSTRUCTIONS FIRST
Write your name and civics group on all the work you hand
in.
Write in dark blue or black pen.
You may use a soft pencil for any diagrams, graphs or rough
working.
Do not use staples, paper clips, highlighters, glue or
correction fluid.
Section A & B [20 marks]:
Answer multiple choice questions in Sections A and B on the
answer sheet provided. This
answer sheet will be collected at the end of the first 30
minutes.
Section C [60 marks]:
Answer all 3 questions on the writing paper provided.
You are reminded of the need for good English and clear
presentation in your answers.
The number of marks is given in brackets [ ] at the end of each
question or part question.
This document consists of 19 printed pages including this
page.
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Section A
For each section there are four possible answers, A, B, C, and
D. Choose the one you consider to
be correct.
1 The relative abundances of the isotopes of a sample of
platinum are shown in the table
below.
Relative Isotopic Mass 194 195 196 197
Relative Abundance 32.3 33.2 26.8 7.7
What is the relative atomic mass of platinum in this sample?
A 194.9 B 195.0 C 195.1 D 195.5
2 In an experiment, 20 cm3 of a 0.500 mol dm-3 iodate IOx
solution was run into an acidified
solution containing an excess of potassium iodide. Both the
iodate and iodide ions reacted
to form iodine according to the following reaction:
IOx (aq) + (2x 1)I (aq) + 2xH+ (aq) xI2 (aq) + xH2O (l)
On titration, the liberated iodine was found to require 0.08
moles of sodium thiosulfate for
complete reaction, forming tetrathionate, S4O62, and iodide
ions.
What is the value of x?
A 2 B 3 C 4 D 8
3 Gaseous particle S has a proton number of m and a charge of
+1. Gaseous particle T has a
proton number of (m 2), the same number of nucleons as S, and is
isoelectronic with S.
Which of the following statements correctly describes S and
T?
A S has more neutrons than T.
B S requires less energy than T when another electron is removed
from each particle.
C T has a larger ionic radius than S.
D T has a charge of 2.
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4 Which graph correctly describes the behaviour of a fixed mass
of an ideal gas?
A
B
C
D
5 Given the following data, predict the type of bonding and
structure present in X, Y, and Z.
Compound
Melting
Point/ K
Electrical Conductivity
in solid state
Electrical Conductivity in
molten state
X 3820 Does not conduct Does not conduct
Y 273 Does not conduct Does not conduct
Z 1074 Does not conduct Conducts well
X Y Z
A giant covalent simple covalent metallic
B simple covalent giant covalent ionic lattice
C giant covalent simple covalent ionic lattice
D ionic lattice simple covalent metallic
P
Density 0
Constant T V
T/ 0C 0
Constant P
P
T/ 0C 0
Constant V PV
V 0
Constant T
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6 The reaction pathway diagram below represents the reaction
occurring with and without a
catalyst.
Which of the following statements is correct?
A E4 is the activation energy for the reverse catalysed
reaction.
B The enthalpy change of the reaction is reduced using a
catalyst.
C The enthalpy change of the forward reaction is (E2 E3).
D Reaction 1 is exothermic.
7 The following equation represents the rate determining step of
a reaction conducted in an
experiment.
CH3Br + OH- CH3OH + Br
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A large excess of OH- was used, resulting in a pseudo-first
order reaction. The initial rate of
this reaction was found to be 5.78 x 10-3 mol dm-3 min-1. Given
that the half life of the
reaction is 24 min, what is the initial concentration of
CH3Br?
A 0.200 mol dm-3
B 0.138 mol dm-3
C 0.000240 mol dm-3
D Cannot be determined from the given information
Energy
Progress of reaction
E1
E2 E3
E4
reactants
products
Reaction 2
Reaction 1
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8 Which of the following shows the correct order of lattice
energies, placing the one with the
lowest numerical value first?
A BaCl2 < SrCl2 < MgCl2
B MgF2 < MgCl2 < MgBr2
C NaCl < MgCl2 < AlCl3
D BaCl2 < MgCl2 < SrCl2
9 Which of the following structural isomers of C8H16 exhibits
both geometrical and optical
isomerism?
A CH2=CHCH2CH2CH2CH2CH2CH3
B (CH3)2C=CHCH(CH3)CH2CH3
C CH3CH=CHCH2CH2CH2CH2CH3
D CH3CH=CHCH2CH(CH3)CH2CH3
10 Which of the following is not the propagation step in the
reaction between ethane and
chlorine under uv light?
A Cl + CH3CH3 CH3CH2 + HCl
B H + Cl2 Cl + HCl
C CH3CH2Cl + Cl CH3CHCl + HCl
D CH3CH2 + Cl2 CH3CH2Cl + Cl
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11 Compound P has the following structure
Compound P
After compound P has reacted with hydrogen gas in the presence
of nickel catalyst, how
many optical isomers will the product have?
A 25 B 26 C 27 D 28
12 Alkene Q, after reacting with hot acidified KMnO4, yields the
following 3 carbon-containing
products.
CO2
Product 1 Product 2 Product 3
What could be the structure of compound Q?
A CH2=CHCH2CH2CH2CH2CH=CH2
B CH3C(CH3)=CHCH2CH2CH=CH2
C CH3C(CH3)=C(CH3)CH2CH=CH2
D CH3C(CH3)=CHCH=C(CH3)2
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13 Lanosterol is a tetracyclic triterpenold which is the
compound from which steroids are
derived. It has the following structure:
Which of the following statements about Lanosterol is true?
A Lanosterol is unable to decolourise liquid bromine.
B When Lanosterol is treated with cold dilute KMnO4, it would
result in a product with 5
OH groups
C When Lanosterol reacts with hot acidified KMnO4, it would
result in 3 products.
D Lanosterol is unable to rotate the plane of polarised
light.
14 Which of the following properties of benzene is not directly
attributed to the stability
associated with its delocalised electrons?
A It would undergo electrophilic reactions.
B It would undergo substitution rather than addition
reactions.
C
The enthalpy change of hydrogenation of benzene is less than 3
times that of
cyclohexene.
D Benzene is less reactive than alkenes.
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15 3-nitrobenzoic acid can be synthesised from a 2-step reaction
of methylbenzene.
Methylbenzene 3-nitrobenzoic acid
Which of the following sequences of this synthesis is
correct?
Step 1
Reagents and
conditions Step 2
Reagents and
Conditions
A Nitration Aqueous HNO3 and
Aqueous H2SO4,
reflux
Oxidation Hot acidified
K2Cr2O7
B Nitration Conc. HNO3 and
Conc. H2SO4, reflux
Oxidation Hot acidified
KMnO4
C Oxidation Hot acidified
K2Cr2O7
Nitration Aqueous HNO3 and
Aqueous H2SO4,
reflux
D Oxidation Hot acidified
KMnO4
Nitration Conc. HNO3 and
Conc. H2SO4, reflux
Step 1 Step 2 Intermediate
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Section B
For each of the questions in this section, one or more of the
three numbered statements 1 to 3 may
be correct. Decide whether each of the statements is or is not
correct (you may find it helpful to put a
tick against the statements which you consider to be
correct).
The responses A to D should be selected on the basis of
A B C D
1, 2, and 3 are correct 1 and 2 only are
correct
2 and 3 only are
correct 1 only is correct.
16 Which of the following solutions contain more ions than 20
cm3 of
1.0 mol dm-3 sodium phosphate, Na3PO4, solution?
1 20 cm3 of 1.4 mol dm-3 H2SO4 solution.
2 15 cm3 of 2.0 mol dm-3 MgCl2 solution.
3 40 cm3 of 1.0 mol dm-3 HNO3 solution.
17 In which of the following pairs is the bond angle in compound
K greater than the bond angle
in compound L?
K L
1 H2Se H2O
2 NH3 XeF4
3 BH3 SF6
18 Given the reaction:
M (g) + N (g) O (g),
which of the following will cause a decrease in the rate
constant?
1 Introducing an inhibitor
2 Decreasing the temperature of the reaction mixture
3 Decreasing the pressure of the system
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19 Which of the following compounds could be formed by the
reaction of propene with aqueous
bromine in the presence of sodium chloride?
1
2
3
20 Under what conditions will bromine react with the compound J
below?
CC
CH
H
HH
H
Compound J
1 In the presence of AlBr3
2 Dissolved in water in the dark
3 In the presence of sunlight
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Section C
1 Phenol was used as the first surgical antiseptic in 1865.
However, due to its carcinogenic
properties, safer antiseptics such as Trichlorophenol (TCP) has
been synthesised which
retains its germicide properties without the toxicity of
phenol.
One of the steps in the production of phenol involves the
Friedel Crafts electrophilic
substitution of benzene using an acid catalyst to form cumene as
shown in the following
reaction:
(a) The enthalpy changes of benzene, propene and cumene are
given below.
H = +815 kJ mol-1
H = +623 kJ mol-1
H = +217 kJ mol-1
H = +125 kJ mol-1
By using the above data, draw an appropriate energy cycle to
calculate the standard
enthalpy change of vapourisation of cumene. [3]
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1(b)
(i) Suggest a chemical test to distinguish between benzene and
cumene. State the
reagents, conditions and the observations with each compound.
[2]
(ii) When cumene is nitrated by a mixture of concentrated nitric
acid and concentrated
sulfuric acid, the product consists largely of two isomers. Draw
the structural
formulae of the two isomers. [2]
(iii) State the type of reaction in b(ii) and outline a
mechanism for the above reaction. [3]
(c) Cumene can be oxidised to a hydroperoxide by passing air
through multiple reactors
containing an aqueous emulsion of cumene at a pH within the
range 8.5 to 10.5 as shown
in the following reaction:
With reference to the hydroperoxide molecule, state the C-Cx-O
bond angle and the
hybridised state about Cx atom.
[2]
x
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1(d) (i) The hydroperoxide molecule is used as a drug to study
the metabolism rate of liver
cells in rats. In a study carried out to determine the rate of
removal of the
hydroperoxide from the rat cells, the reaction was found to have
a constant half life
of 2.7 hours. Sketch a graph to show how the concentration of
hydroperoxide
changes with time, assuming the initial concentration of
hydroperoxide is
0.05 mol dm-3
[2]
(ii) What would be the qualitative effect on the rate constant
by changing the
concentration of the hydroperoxide molecule? [1]
(e)
Phenol TCP sodium trichlorophenoxide
State and explain the order of increasing boiling points of
phenol, TCP and sodium
trichlorophenoxide. [3]
(f) When 0.95 g of TCP is completely vapourised in a gas syringe
at 300 C and
101 kPa, 220 cm3 of gaseous TCP is produced. Calculate the
relative molecular
mass of the gas produced and suggest why there is a difference
between the
theoretical value and the value calculated. [2]
[Total: 20 marks]
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2 Ethane-1,2-diamine is used in large quantities for the
production of many industrial chemicals
such as in pharmaceuticals and agrichemicals. Ethane-1,2-diamine
is manufactured by reacting
ammonia and 1,2-dichloroethane as shown in the following
equation:
(a) (i) Explain with the aid of a suitable diagram why boron
trifluoride reacts with
ethane-1,2 -diamine in a molar ratio of 2:1.
(ii) State and outline the mechanism for the formation of
1,2-dichloroethane from a
suitable alkene of your choice.
(iii) Due to the bifunctional nature of ethane-1,2diamine, it
readily forms heterocycles
such as imidazolidines as shown below. Predict, with the aid of
a suitable diagram,
the solubility of imidazolidines in water.
[8]
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2(b) Ethane-1,2-diamine, (abbreviated as en), forms an ion of
the molecular formula
IV2
22Pt en C
l .
To study the chemistry of this ion, a radioactive isotope of
chlorine, *Cl was used.
The reaction between *Cl and IV2
22Pt en C
l can be represented by the following
equation:
II
IV IV
2
2Pt en2 2
22 2Pt en C C Pt en C C C
l l l l l
The rate of the above reaction is slow and can be increased in
the presence of
II2
2Pt en
catalyst. The results of some investigation of the rate of this
reaction are
shown below.
Experiment
IV2
22Pt en Cl
/ mol dm3
[*Cl-]
/ mol dm3
II2
2Pt en
/ mol dm3
initial rate
/ mol dm3 s1
1 0.80 0.10 0.20 0.409
2 0.40 0.05 0.10 0.049
3 0.40 0.05 0.20 0.102
4 0.20 0.05 0.10 0.025
(i) Determine the order of reaction with respect to each
reactant and hence deduce the
rate equation.
(ii) Using data from Experiment 1, calculate a value for the
rate constant, k, giving its
units.
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2(b) (iii) With the sketch of the Boltzmann distribution,
explain how the use of a catalyst can
speed up the rate of a reaction. Also, state the effect of the
catalyst on the rate
constant, k.
[6]
(c) An experiment is conducted to determine the standard
enthalpy change of neutralisation
between ethane-1,2diamine, a diacidic base, and hydrochloric
acid.
Aqueous ethane-1,2diamine is added to 45 cm3 of 1 mol dm-3
aqueous hydrochloric acid.
The changes in temperature are recorded and the following graph
was obtained.
(i) Using the graph obtained, calculate the standard enthalpy
change of neutralisation,
assuming that 4.2 J is required to raise the temperature of 1
cm3 of solution by 1 oC.
(ii) Given that S= -205 J mol-1 K-1, calculate G and hence
predict its spontaneity at
298K.
(iii) Is the spontaneity of the above neutralisation process
dependent on temperature?
[6]
[Total: 20 marks]
Temperature/oC
Volume of base added/cm3
30.9
25.6
25.00
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3(a) Hex-1-ene is a co-monomer used in the production of
polyethene, which is widely used to
manufacture plastic shopping bags. Some reactions of hex-1-ene
are shown below.
Compound A
(i) Name and describe the type of reaction mechanism that occurs
in Step 2.
Use R-CH2CH3 to represent the alkane in Step 2 while R =
CH3(CH2)3
(ii) State the reagents and conditions for Step 1.
(iii) Compound A can exist as a pair of stereoisomers. Draw
structural formulae to represent
the isomers.
[4]
(b) Sulfuryl chloride is a very good source of Cl2 which reacts
with hex-1-ene to form an
important industrial solvent.
(i) State the electronic configuration of chlorine, Cl.
(ii) Sketch the shape of the singlyoccupied orbital in an atom
of Cl.
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3(b) (iii) With reference to the Data Booklet, briefly explain
why the first ionisation energy of
sulfur is lower than that of chlorine but the second ionisation
energy of sulfur is
similar than that of chlorine.
[5]
(c) Halogens undergoes disproportionation in hot metal
hydroxides to form chlorates (VII) and
bromates (VII), which contain only the XO4- ion (X = Cl or Br)
as well iodates (VII) which
contains the ions IO53-, IO6
5- and IO4- .
(i) Draw the dot and cross diagram for IO65- and hence state the
shape of the ion.
(ii) Consider the following ions: IO53-, IO6
5- and IO4-
State the polarity of the electric plate which the above ions
would be deflected to
and also the ion which gives the most deflection.
(iii) The purity of iodates (VII) can be determined by adding an
acidified solution of
potassium iodide and titrating the iodine produced with aqueous
sodium
thiosulfate.
In one such analysis, a sample of 0.200 g of sodium iodate
(VII), Na5IO6, was
dissolved in water and treated with an excess of acidified KI to
yield iodine and
water as the only products. The iodine liberated required 22.0
cm3 of
0.100 mol dm-3 sodium thiosulfate to reach the end-point.
a) Using half equations, write a balanced ionic equation for the
reaction of
iodate (VII) with acidified iodide.
b) Hence, calculate the purity of the sodium iodate (VII) in the
sample.
[7]
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3(d) Potassium iodate (VII), KIO4, is used as a source for
iodine as an ingredient in baby
formula milk. Potassium iodate (VII) is also occasionally used
as a maturing agent in
baking.
(i) The lattice energy of KIO4 is 1527 kJ mol-1 while the values
of the enthalpy change of
hydration of the ions are listed below:
Ions Hhyd / kJ mol-1
K+ 1420
IO4- 295
Calculate the enthalpy change of solution of potassium iodate
with the aid of an energy
level diagram.
(ii) By using your answer from (d)(i), and given the entropy
change of solution of
potassium iodate (VII) is positive, predict whether potassium
iodate is soluble in water
at room temperature and pressure. Give your reasoning,
[4]
[Total: 20 marks]