Chemistry Intensive Revision Program - Set 1 SEKOLAH TINGGI MELAKA (Super Thinkers’ Module) CHEMISTRY PROGRAM ULANGKAJI INTENSIF (PUI) (Intensive Revision Program-IRP) Panitia Sains (Kimia) MELIORA HIC SEQUAMUR KE ARAH KECEMERLANGAN PENDIDIKAN Set 1 1
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Chemistry Intensive Revision Program - Set 1
SEKOLAH TINGGI MELAKA(Super Thinkers’ Module)
CHEMISTRY
PROGRAM ULANGKAJI INTENSIF(PUI)
(Intensive Revision Program-IRP)
Panitia Sains(Kimia)
MELIORA HIC SEQUAMURKE ARAH KECEMERLANGAN PENDIDIKAN
Set 1 1
Chemistry Intensive Revision Program - Set 1 PAPER 2 – STRUCTURE
SECTION A
1 Graph 1 shows the temperature against time of solid substance X when heated. Substance X is an organic compound and flammable.
GRAPH 1
(a) Draw a diagram of the set-up of the apparatus used to determine the melting point of substance X.
[ 2 marks](b) (i) State the melting point of substance X
........................................................................................................................................................[ 1 mark]
(ii) What is the state of matter of substance X at :
PQ : .....................................................................................................................................................
RS : ....................................................................................................................................................[ 2 marks]
(iii) Explain why the temperature remains constant from Q to R.
..............................................................................................................................................................
..............................................................................................................................................................[ 2 marks]
(iv) State how the movement of substance X particles changes between R and S during heating.
……………………………………………………………………………………………………………………[ 1 mark]
Set 1 2
Temperature / 0C
Time/s
80
30
360
P
Q R
S
Chemistry Intensive Revision Program - Set 1 (c) If substance X is cooled to the room temperature without stirring, draw the graph of temperature against
time obtained.
[ 2 marks](d) Identify subtance X
.....................................................................................................................................................................[ 1 mark]
2 Diagram 2 shows part of the Periodic Table of Elements.V,W,X,Y and Z do not represent the actual symbol of the elements.1 18
2 13 14 15 16 17W X V Z
Y
DIAGRAM 2(a) Write the electron arrangement of V ion.
…………………………………………………………………………………….....................................
[1 mark ](b) (i) Which of the element is not chemically reactive.
. ........................................................................................................................................... [1 mark ]
(ii) Explain your answer in (b)(i).
........................................................................................................................................... [1 mark ]
(c) V and Y are located in the same group in the Periodic Table of Elements. (i) Which of the element is more reactive?
..............................................................................................................…......................... [1 mark ]
(ii) Explain your answer in (c)(i).
…………………………………………………………………………......................................
…………………………………………………………………………......................................
…………………………………………………………………………...................................... [3 marks]
(d) Y reacts with iron to form a compound.
(i) State one property of the compound formed.
…………………………………………………………………………………........................................ [1 mark]
Set 1 3
Chemistry Intensive Revision Program - Set 1 (ii) Draw a labeled the set up of apparatus of the reaction between Y and iron, Fe
[ 2 marks]
3 The table 3 shows melting point, boiling point and electrical conductivity of substance P, Q, R, and T .
\Substance
Melting point (oC) Boiling point (oC )
Electrical conductivity
Solid Molten
P 805 1460 No Yes
Q 1549 2950 Yes Yes
R -210 -153 No No
T -7 59 No No
Table 3(a) Which of the substances is a metal ?
……………………………………………………………………………………………………………………. [1 mark]
(b) (i) state the type of particle in substance P ?
……………………………………………………………………………………………………………………….. [1 mark]
(ii) Explain why substance P cannot conduct electricity in solid but can conduct electricity molten state. ..................................................................................................................................................................
.................................................................................................................................................................. [2 marks]
(c) (i) What is the physical state of R and T at room temperature ?
R : ............................................
T : ...................................... [2 marks]
(ii) Draw the arrangement of particles in substance T at room temperature .
[ 2 marks ]
Set 1 4
Chemistry Intensive Revision Program - Set 1 (iii) Explain why the melting and boiling points of substance R and T is low ?
………………………………………………………………………………………………………………………
……………………………………………………………………………………………………………………….
[ 2 marks ]
4 The diagram 4 shows the electron arrangement of compound J. Compound J formed from reaction between element X and element Y
__ 2 + __
Y Y X Y
Diagram 4
(a) How are Y ion and X ion formed from their respective atoms?
Y ion: …………………………………………………………………………………………………..
X ion : …………………………………………………………………………………………………[ 2 marks]
(b) (i) Write the formula for compound J
........................................................................................................................ [1 mark]
(ii) Name type of bond in compound J
........................................................................................................................ [1 mark]
(iii) Write the chemical equation for the reaction between element X and element Y to form compound J.
..............................................................................................................................................
[1 mark]
(c) (i) Write the electron arrangement for atom of element X and Y
X :…………………………………….
Y : ………………………………….. [2 marks]
(ii) Between atom of element X and Y, which one has a smaller size.
.........................................................................................................................................
[1 mark]
(iii) Explain your answer in (b) (ii)
..........................................................................................................................................
..........................................................................................................................................
[3 marks]
Set 1 5
Chemistry Intensive Revision Program - Set 1 (d) Y can react with carbon to form a compound. Draw the electron arrangement for the
compound formed.[Given that proton number for carbon is 6]
[2 marks]
5 In an experiment to determine the empirical formula of an oxide of copper , the combustion tube with the porcelain dish are weighed. Oxide of copper is added into the porcelain dish and the tube is weighed again. The oxide of copper is heated strongly. After the set of apparatus cools down to room temperature the combustion tube with its content is weighed again.
The following data is obtained.
Mass of combustion tube + porcelain dish = 19.60 gMass of combustion tube + porcelain dish + oxide of copper = 25.68 gMass of combustion tube +porcelain dish + copper = 24.46 g
(a) What is meant by empirical formula?
……………………………………………………………………………………………………………… [1 mark]
(b) Draw a labeled diagram of the set-up of the apparatus for the experiment.
[2 marks](c) Calculate the empirical formula of the oxide of copper.
[Given that the relative atomic mass of O=16 , Cu=64]
[3 marks](d) Write the chemical equation for the reaction in the experiment.
…………………………………………………………………………………….................................... [1 mark]
Set 1 6
Chemistry Intensive Revision Program - Set 1 (e) Before oxide of copper is heated, hydrogen gas is allowed to pass through the apparatus until
all the air in the combustion tube is completely removed.Describe the steps that should be taken to ensure that all air in the combustion tube has been removed.
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
……………………………………………………………………………………………………………… [3 marks]
(f) (i) Can the empirical formula of magnesium oxide be determined using the same method as above? Explain your answer.
………………………………………………………………………………….....................................
…………………………………………………………………………………..................................... [2 marks]
(ii) Draw a labeled diagram of the set-up of the apparatus for the experiment
[2 marks]6. Diagram 6 shows shows the chemical symbols which represent elements R, S and T.
R S TDiagram 6
(a) (i) Write the electron arrangement of atom T
………………………………………………………………………………………………………………[ 1 mark]
(ii) State the period and the group for element T in the Periodic Table.
Period : ….……………………………………………………………..................................................
Group : ……………………………………………….………..........................................................[2 marks]
(b) Atoms of R and S can react to form a compound.
(i) Name the type of bond in the compound formed between atoms R and S.
………………………………………………………………………………………………………………[1 mark]
(ii) State one physical property of the compound formed in b(i)
……………………………………………………………………………………………………………..[1 mark]
Set 1 7
17 6 11
35 12 23
Chemistry Intensive Revision Program - Set 1 (c) (i) Atom of R and T can also react to form compound. Draw the electron arrangement for the
compound formed.
[2 marks] (ii) Name the force that exist between particles in the compound formed .
........................................................................................................................................................ [ 1 mark]
(iii) The melting point of the compound formed is 801◦ C and its boiling points is 1413 ◦C. What is te state of matter for this compound at 1000◦ C.
…….............................................................................................................................................
[ 1 mark]
(d) Arrange R, S and T according to the increase the atomic size
………………………………………………………………………………………………………………[1 mark]
7 Lactic acid is an acid produced in milk by bacteria that causes the milk to taste sour. Table 7 shows the percentage of composition by mass of each element in lactic acid.
Element Percentage
Carbon 40.00
Hydrogen 6.67
Oxygen 53.33
TABLE 7
(a) Based on the information above, calculate the empirical formula of lactic acid.Given that the relative atomic mass of H = 1 ; C = 12 ; O = 16
[3 marks](b) Relative molecular mass of lactic acid is 90. Determine the molecular formula of lactic acid.
[2 marks](c) Calculate the number of hydrogen atom in 1 mol of lactic acid?
Given that Avogadro number ,NA = 6.02 × 10 23 mol-1
[2 mark](d) Calculate the number of moles of 4.5 g lactic acid.
Given that the relative atomic mass of H = 1 ; C = 12 ; O = 16
[1 mark]
Set 1 8
Chemistry Intensive Revision Program - Set 1 (e) Vinegar or ethanoic acid has a similar empirical formula with lactic acid.
(i) Given that three molecules of ethanoic acid have the same mass as two molecules of lactic acid. What is the relative molecular mass of ethanoic acid?
[1 mark](ii) Determine the molecular formula of ethanoic acid.
[2 marks]
8 Table 8 shows formula of four ions.
Name of ions Silver ion Zinc ion Nitrate ion Chloride ion
Formula of ions Ag+ Zn2+ NO3- Cl-
TABLE 8(a) Write the formula for each compound below :
(i) Silver nitrate ………..…..........................................................................................
(ii) Zinc chloride : .......................................................................................................
(ii) Silver chloride : .......................................................................................................
(iii) Zinc nitrate : .......................................................................................................[4 marks]
(b) When silver nitrate solution is added to zinc chloride solution, white precipitate, silver chloride and zinc nitrate solution are formed.
(i) Identify the reactants and products of the reaction.
Reactants : .......................................................................................................................
Products : ....................................................................................................................... [2 marks]
(ii) Write the chemical equation for the reaction occurs in (b).
...........................................................................................................................................[1 mark]
(c) The following equation shows the decomposition of silver nitrate by heat.2AgNO3 2Ag + 2NO2 + O2
If 85.0 g of silver nitrate is heated completely, calculate : (i) the mass of silver formed.
Given that the relative atomic mass of N =14; O = 16; Ag =108
[3 marks](ii) the volume of oxygen gas formed at room conditions.
Given that the Molar volume : 24 dm3 at room conditions
[2 marks]
Set 1 9
Chemistry Intensive Revision Program - Set 1
ESSAY SECTION B9 (a) Diagram 9 shows the models of atoms which were developed by Ernest Rutherford and Neils Bohr and modern atomic model. Electron moves outside the nucleus
Nucleus contains protons Rutherford’s model Bohr’s model
DIAGRAM 9
(i) Describe th atomic structure of the Bohr’s model [4 marks]
(ii) What is the difference in the position of electrons between the Rutherford’s model and Bohr’s model
[2 marks](iii) Draw the electron arrangement of an atom that consist of 13 electrons using the modern atomic model
[2 marks]
(b) Chlorine has two isotopes which are chlorine-35 and chlorine-37.The proton number of chlorine is 17. X
(i) Write the symbol for one of the isotope of chlorine in the form of A Z [3 marks]
(ii) Compare the number of sub atomic particles in these two isotopes [4 marks]
(c) Describe fully the atomic structure for chlorine isotope that you have stated in 1(b)(i) [5 marks]
ESSAY SECTION C
10 (a)
Explain the above statement.Given that relative molecular mass of carbon dioxide = 44 g mol –1,
relative molecular mass of oxygen = 2 g mol –1 [3 marks]
(b) (i) What is meant by empirical formula? [ 1 mark]
(ii) Describe an experiment in the laboratory to determine the empirical formula of magnesium oxide. Your answer should consist of the following. Procedures of the experiment Calculation involved Precautions need to be takenGiven that relative atomic mass of Mg = 24, O = 16
[13 marks]
(c) Magnesium can reduced copper oxide to copper.Explain why the empirical formula of the copper oxide cannot be determined by heating the mixture of copper oxide and magnesium powder.
[ 3 marks]
Set 1 10
The volume of 2.2 g of carbon dioxide gas is less than the volume of 2.2 g of hydrogen at the same temperature and pressure.
Electron
Shell
Nucleus containsprotons
Modern atomic structure
Chemistry Intensive Revision Program - Set 1 11 Table 11 shows the proton number of atoms P, Q and R.
Element P Q R
Proton number 8 12 17
TABLE 11(a) Based on electron arrangement, explain the formation of chemical bond between
(i) element P and element P [5 marks ]
(ii) element Q and element R [7 marks ]
(b) Gas P reacts with element Q to produce a white solid.(iii) Write a chemical equation for the reaction between gas P and element Q. (ii) State three physical properties of the white solid. [ 4 marks] ]
(c) What is the position of elelment Q in the Periodic Table of the elements? Explain how do you obtain your answer. [ 4 marks ]
PAPER 312. The diagram below shows the apparatus set-up for the experiment to determine the freezing point of substance X.
The diagram below shows the thermometer reading for the cooling of substance X at certain time intervals.
Set 1 11
thermometer
Substance X
Volumetric flask
90
95
85
0 Minute 1st minute 2nd Minute 3rd minute
85
90
80
85
90
80
85
90
80
85
90
85
90
80
75
80
70
70
75
65
4th minute 5th minute 6th minute 7th Minute
Chemistry Intensive Revision Program - Set 1 (a) Record the thermometer readings shown in the diagram above by completing the table below.
[3 marks](b) Draw the graph of temperature against time on the graph paper provided.
[3 marks](c) Based on the graph in (b),
(i) State the change in temperature of substance X for the whole experiment.
...........................................................................................................................
...........................................................................................................................
........................................................................................................................... [3 marks](ii) State the inference for your answer in (c) (i) .
...........................................................................................................................
........................................................................................................................... [3 marks]
(d) What is the freezing point of substance X? Show and label it on the graph how you obtained the answer.
…………………….............…………………………………………………………… [3 marks](e) Based on this experiment, what is meant by freezing point?
……...…………………………………………………………………………………
……...………………………………………………………………………………… [3 marks]
(f) If substance X is heated from room temperature until 100oC, what is the temperature when substance X starts to melt? Explain your answer.
…………………………………………………………………………………....................... [3 marks]
13
An experiment is carried out to investigate the statement above.The table below shows the apparatus set up and the observations for the experiment to determine the reactivity of the Group 1 elements based on their reactions with water.
Apparatus set-up Observation towards the metal
Lithium moves slowly on the surface of the water with a “hiss” sound.
Potassium moves vigorously and randomly on the surface of the water with a “hiss” sound.
Set 1
time/minute 0 1 2 3 4 5 6 7
Temperature/ oC
12
Elements in Group 1 of the Periodic Table of Elements can be arranged based on the reactivity of the elements with water.
water
))
)))
Potassium
)) ) )
water
Lithium
Chemistry Intensive Revision Program - Set 1
Sodium moves quickly and randomly on the surface of the water with a “ hiss” sound.
(a) State the variables that are involved in the experiment.Name of variables Action to be taken(i) Manipulated variable:
……………………………………..
……………………………………..
(i) The way to manipulate variable:
………………………………………..
………………………………………...
(ii) Responding variable:
……………………………………
……………………………………
(ii) What to observe in the responding variable:………………………………………..
………………………………………..………
(iii) Controlled variable:
……………………………………..
……………………………………..
(iii) The way to maintain the controlled variable:
………………………………………
………………………………………
[6 marks]
(b) State one hypothesis for the experiment.
………………………………………………………………………………………
……………………………………………………………………………………… [3 marks]
(c) Based on the observations in the figure above, arrange lithium, potassium and sodium in the descending order of reactivity of metals towards water.
Descending order of reactivity of metals towards water. [3 markah]
(d) Solution X was produced from the reaction of sodium with water. Classify the ions that exist in solution X into positive ions and negative ions.
Positive Ions Negative Ions
[3 marks]
Set 1 13
water
sodium
)) )
“When lithium metal is put in water, it moves very slowly on the surface of the water. When sodium metal is put in water, it moves quite fast and produces “hiss” sound. When potassium metal is put in water, it moves very fast and produces small explosions”. Metal
Chemistry Intensive Revision Program - Set 1
14
Plan an experiment in the laboratory to investigate the reactivity of lithium, sodium and potassium with water and describe the effect of the solution produced towards a red litmus paper. The planning of your experiment must consist of the following:
(a) Aim of experiment (b) Statement of the hypothesis (c) All the variables
(d) List of substances and apparatus(e) Procedure of the experiment(f) Tabulation of data
[17 marks]
Set 1 14
Water
Chemistry Intensive Revision Program - Set 1 Sample Answer
Section A
1 (a)
[Functional diagram ][ Labeled] 1
1
(b) (i) 80 oC 1
(ii) PQ : solidRS : liquid
11
(iii) The energy is absorbed to overcome the forces of attraction between the particles
11
(iv) The particles move faster 1
(c)
[The shape of the graph is correct and 80 0C on graph][ Both axis are labeled with unit ]
11
(d) naphthalene 111
2 (a) 2.8.8 1(b) (i) Z 1
(ii) Achieve octet electron arrangement // achieve 8electron in the outermost shell // 8 valence electron 1
(c) (i) V 1
(ii) The atomic size of V is smaller than the atomic size of Y 1The attraction between the nucleus and the outermost occupied shell is stronger in an atom V than an atom Y 1It is easier for atom V to receive electron 1
Set 1 15
Temperature / 0C
Time/s
80
Boiling tube
Heat
Substance X
water
Thermometer
Chemistry Intensive Revision Program - Set 1 (d) (i) High melting / boiling point// dissolve in water// do not dissolve in
organic solvents // conduct electricity in aqueous solution or molten state 1
(ii)
Functional diagram and heating is shown 1Y/Chlorine gas and iron labeled 1
10 3 (a) Q 1
3(b)(i) Ion 13(b)(ii) solid state : Ions are not freely moving// ions are in a fixed position.
molten state : Ion can move freely11
3(c)(i) R : GasT : Liquid
1
3(c)(ii)2
3(c)(iii) - Van der waal/intermolecular forces are weak- Small amount of heat is required to overcome it
11
Total 10
4 (a) Atom Y receive one electronAtom X receive two electron
11
(b) (i) X2Y 1
(ii) Ionic bond 1
(iii) 4X + Y2 → 2X2Y 1
(c) (i) X : 2.8.2Y : 2.8.7
11
(ii) Y 1
(ii) - Atom X and atom Y have the same number of shells occupy with electrons- The number of proton in the nucleus of atom Y is more than X- Nulcei attraction to the electrons in the shells of atom Y is stronger than X
111
(d) - Electron arrangement all atoms are correct - One carbon atom share four pairs of electrons with 4 Y atoms
11
Total 12
5 (a) Formula that shows the simplest ratio of the number of atomsfor each element in the compound. 1
Set 1 16
Y/Chlorine gas
Iron
Heat
Chemistry Intensive Revision Program - Set 1
(b)
Functional diagram an heating is shown 1Dry hydrogen gas and oxide of copper are labelled 1
(c) Cu O
24.46 – 19.60 / 4.86 25.68 – 24.46 / 1.22 1
4.86 / 0.076 1.22 / 0.076 1 64 16
CuO 1(d) CuO + H2 Cu + H2O 1(e) Collect the gas in a test tube 1
Put lighted wooden splinter at the mouth of the test tube 1No pop sound 1
(f) (i) No 1Magnesium more reactive than hydrogen //Hydrogen less reactive than magnesium // hydrogen below magnesium in reactivity series. 1
(ii)
Functional diagram and heating is shown1 Magnesium is labeled 1
14
6 (a) i 2.8.1 // 2,8,1 1
ii 31
11
(b) i Covalent bond 1
ii Low melting point and boiling point//insoluble/does not dissolve in water//soluble/dissolve in organic solvent//does not conduct electricity in any state
Choose one1
(c) (i)
Number of electrons for ion T and ion R are correctCharge of ions and ratio of ion T to ion R are correct 1
1(ii) Elecrostatic 1
(iii) Liquid / molten state 1
(d) S, R,T 1
Set 1 17
R
-+
T
Dry hydrogen gas
Oxide of copper
Heat
Heat Magnesium
Chemistry Intensive Revision Program - Set 1
Total 10
7 (a)Element C H O
Number of moles (mol)
= 3.33
= 6.67
= 3.33
Ratio of moles 1 2 1
1
1
The empirical formula of the compound is CH2O 1(b) n [ 12 + 2(1) + 16 ] = 90
n =
= 3
Molecular formula of lactic acid is C3H6O3
1
1(c) One molecule of lactic acid contains 6 hydrogen atoms//
1 mol of lactic acid contains 6 mol of hydrogen atoms1 mol of lactic acid contains 6 × 6 .02 × 10 23 hydrogen atoms
11
(d)The number of mole of lactic acid =
= 0.05 mol 1
(e) 3 × Mr of ethanoic acid = 2 × Mr of lactic acid
Mr of ethanoic acid =
= 601
(f) n (30) = 60 n = 2Molecular formula of ethanoic acid is C2H4O2 / CH3COOH
1
111
8 (a) (i) AgNO3 1 (ii) ZnCl2 1 (iii) AgCl 1 (iv) Zn(NO3)2 1
(b) (i) Silver nitrate and zinc chloride 1
Silver chloride and zinc nitrate 1
(ii) 2AgNO3 + ZnCl2 2AgCl + Zn(NO3)2 1(c) (i)
Number of moles of AgNO3 =
= 0.5 mol1
2 moles of AgNO3 produce 2 moles of Ag0.5 mole of AgNO3 produce 0.5 mole of Ag 1Mass of Ag = 0.5 × 108
= 54 g 1 (ii) 2 moles of AgNO3 produces 1 mole of O2
0.5 mole of AgNO3 produces 0.25 mole of O2 1Volume of O2 = 0.25 × 24
= 6 dm3 110
SECTION B9 (a) (i) 1. Atom consist proton and electron 1 2. Electrons in the shell 1 3. Protons are in the nucleus 1
Set 1 18
Chemistry Intensive Revision Program - Set 1 4. The nucleus in the middle of the atom 1
(ii) 1. Rutherford’s model: Electrons outside the nucleus 1 2. Bohr’s model: Electrons in the shell 1 (iii)
1. Atom with nucleus and the number of shells is 3 1 2. Correct number of electrons: 2.8.3 1
(b) (i) 35 37 Cl Cl
17 17 1. Symbol of an element 12. Nucleon number 13. Proton number 1
(ii) 1. Chlorine-35 and chlorine-37 have 17 protons// The electron arrangements of chlorine-35 and chlorine- 37 are 2.8.7 1
2. The number of neutron in chlorine-35 and chlorine- 37 are 18 and 20 respectively// The nucleon number of chlorine-35 and chlorine- 37 are 35 and 37 respectively 1
(c) 1. Nucleus is at the centre of the atom2. Nucleus contains 17 protons, which are positively charged particles3. The number of neutrons are 18/20 which are neutral particles4. The nucleon number is 35/375. Electron cloud consist of 17 electrons6. Electron which is negatively charged particles move around the nucleus// Electron is located outside the nucleus/in the shell 7. Electron arrangement is 2.8.7// The number of shells field with electrons are 3 any 5
Total: 20
SECTION C
10 (a) Number of mole of carbon dioxide = = 0.05 mol 1
Number of mole of hydrogen = = 1.1 mol 1
The number of mole of carbon dioxide is smaller; therefore, its volume is smaller than
the volume of hydrogen 1(b) (i) The empirical formula of a compound is the formula that shows the simplest
whole number ratio of atoms of each element present in the compound. 1(ii) [Material and apparatus ]
[Magnesium ribbon, sand paper, crucible with lid, tongs, Bunsen burner, tripod stand, pipe-clay triangle and balamce.] or [diagram] 2
[Procedure] A crucible and its lid is weighed and its weight is recorded. 1 A 10 cm length of magnesium ribbon is coiled loosely and is placed in the crucible. 1 The crucible with its lid and content are weighed again and the weight is recorded . 1 The crucible is heated strongly without its lid. 1 When the magnesium starts to burn, the crucible is covered with its lid. Using a pair of tongs, the lid is lifted at intervals. 1 When the burning is completed, the lid is removed and
the crucible is heated strongly for 2 minutes. 1 The rucible is allowed to cool to room temperature. 1 The crucible and its lid and content are weighed again and its weight is recorded. 1
max 5[Precautions taken]
The magnesium ribbon is cleaned with sand paper to remove the layer of magnesium oxide on the surface.
Set 1 19
Chemistry Intensive Revision Program - Set 1 The crucible must cover with its lid to prevent the white fumes of
magnesium oxide of escaping. The processes of heating, cooling and weighing are repeated until
a constant mass is obtained. [any two of the above] 2
[ Results ] Crucible + lid = a g
Crucible + lid + magnesium = b g Crucible + lid + magnesium oxide = c g 1
[ Calculation ]
Element Magnesium OxygenMass(g) b-a c-bNumber of moles of atoms b-a/24 c-b/16Simplest ratio of moles X y
2 Empirical formula = MgxOy 1
(c) 1 Unable to make sure that all the magnesium is oxidised . 1
2 The products (Cu and MgO) cannot be separated. 13 The mass of copper and oxygen cannot be determined. 1
2011 (a)(i) 1. Two atoms of P combine through covalent bond. 1 2. Each atom of P needs two more electrons to achieve octet electron arrangement.
3. Each atom of P contributes two electrons to each other for sharing. 14. Two atoms of P share two pairs of electrons. 15. A double covalent bond is formed.
P P
2
(ii) 1. Atom Q and atom R combine through ionic bond. 12. To achieve octet electron arrangement, 13. atom Q with 6 valence electrons loses two electrons to form Q2+ ion 14. Two atom R, each atom with 7 valence electrons
gains one electron to form R- ion. 15. Q2+ ion and R- ion are attracted to each other by strong electrostatic force.1
_ 2+ _
R Q R
2
(b)(i) 2Q + P2 2QP 1
(ii) 1. Have high melting point 12. Usually soluble in water 13. Conduct electricity in the molten state or aqueous solution. 1
1. Element Q is located in Group 2 12. because it has two valence electrons 1
Set 1 20
Chemistry Intensive Revision Program - Set 1 3. Element Q is located in Period 3 14. because it has three shells occupied with electrons 1
20PAPER 3
Question Rubric12 (a) Able to record all the readings correctly to 1 decimal place.
Time (minute)
0 1 2 3 4 5 6 7
Temperature (oC)
95.0 89.0 84.5 83.0 83.0 83.0 77.0 70.0
12 (b) Able to draw the graph with the following elements:: X-axis is labeled(minute) and y-axis temperature(oC) with consistent scales
Size of the graph is at least half the page of the graph paper.
All the points are plotted correctly
Curve of the graph is correct and smooth
Question Rubric12 (c) (i) Able to explain the change of temperature with time from the graph.
Suggested answer:
Set 1 21
Temperature/oC
Melting point
Time/minute
Graph of temperature against time
Chemistry Intensive Revision Program - Set 1 In the first 3 minutes, the temperature of substance X will decrease from
95oC to 83oC. Constant temperature at 83 oC for 3 minutes.
The temperature decreases again after 83 oC 12 (c) (ii) Able to make the correct inference.
Suggested answer: Temperature decreases because heat is released to the surrounding.
Temperature is contant because heat released to the surrounding is balanced by the heat released when bonds are formed.
The freezing process is at 83 oC // solid and liquid X exist together
12 (d) Able to state the freezing point accurately based on the graph with the correct unit.
Dotted line is shown on the graph.
Labeling the freezing point at temperature axis. 12 (e) Able to give the meaning of freezing point accurrately.
Suggested answer:Freezing point is the constant temperature at 83oC even though substance X is let to cool to room remperature.
12 (f)
Able to predict the melting point of substance X accurately with unit and with correct reasons.Suggested answer :83.0 oCValue of melting point substance X is the same as its freezing point.
Question
Rubric Rubric
13 (a) Able to predict the manipulated variable, the responding variable and the constant variable completely.
Suggested answer: Manipulated variable : metals of Group 1 elements // sodium, lithium, potassium.
Responding variable: the reactivity of the reaction with water // the speed of movement on the water surface
Constant variable: size/mass of metals. Volume of water
Able to state how to control the manipulated variables correctly
Suggested answer: Repeat the experiment by using the metals of sodium, lithium and potassium
Able to state correctly the way to control the manipulated variable
Suggested answer: To observe how fast the metals move on the surface of water.
Able to use the metal granules with the same sizeSuggested answer :Use the metal granules with the same size.
13 (b) Able to state the relationship between the manipulated variable and the
responding variable correctly..
Suggested answer: The reactivity of Group 1 elements increases going down the group.
13 (c) Able to arrange correctly the reactivity series of the metals according to descending order. Answer: potassium, sodium, lithium
13 (d) Able to classify the ions correctly.[to name or write all the formula of the ions correctly at the cations and anions group.]Answer: positive ion/ cation : sodium ion/ Na+, hydrogen ion/ H+
Set 1 22
Chemistry Intensive Revision Program - Set 1 Negative ion/anion : hydroxide ion/ OH-
Question
Rubric Score
14(a) [Able to state the aim of experiment accurately]To compare the reactivity of lithium, sodium and potassium based on the reaction with water and describing the effect of the solution towards the red litmus paper.
3
14(b) HypothesisMetals of lithium, sodium and potassium show different rate of reactivity with water and the solution formed turns red litmus paper to blue.
14(c) Variablesa) Manipulated variable :type of metals b) Responding variable : reactivity of reaction c) Constant variable : water and temperature
3 x12x11x1
14(d) [Able to list the correct and complete substances and apparatus.]Substances and Apparatus
Lithium, sodium and potassium metals with water, basin, knife, forceps, blue litmus paper and white tile.
3
14(e) [Able to give all the procedures correctly, steps 1 - 7]1. Lithium metal is cut into a small piece2. The paraffin oil on the surface of the metal is wiped with the
filter.3. A basin is filled with water. 4. Lithium metal is put on the surface of the water with a pair of forceps. 5. Reactivity of the reaction is observed and recorded.6. The experiment is repeated with sodium and potassium metals.
3
14(f) [Able to show the accurate tabulation of data with correct title.]
Metals ObservationsLithiumSodium
Potassium
3
Set 1 23
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