CONFIDENTIAL
4541/2
Chemistry
Paper 2
September
2014
SIJIL PENDIDIKAN
MAKTAB RENDAH SAINS MARA
2014
CHEMISTRY
Paper 2
MARKING SCHEME
FOR EXAMINERS USE ONLY
ATTENTION
This marking scheme is Confidential and copyright of MARA. It is
exclusively for examiners use only. No information in this marking
scheme is allowed to be made known to anyone. This marking scheme is
not permitted to be copied in any written or printed form
CONFIDENTIAL
NO.
1
(a) (i)
MARKING SCHEME
PAPER 2 (SECTION A)
MARK
TOTAL
1
1
1
1
N / Detergent
P : Aspirin/ paracetamol/ codeine
Q : Antibiotic
1
1
(ii)
To relieve/ reduce pain // as pain killer
[r: to cure pain]
(iii)
To make sure all the bacteria are killed//bacteria become
immune/resistant to the given medicine
[r: virus/ microorganism/ germs/ fungi]
TOTAL
(ii)
M : soap
N : detergent
SUB
Cleansing agent
M
N
(iii)
(b)(i)
CONFIDENTIAL
Observation
Oily stain remain //Cloth is still dirty
No oily stain // Cloth is clean
NO.
2(a)
(b)
(c)(i)
MARKING SCHEME
Na / Mg / Al
2.8 / 2,8
[r : 2:8]
Forces of attraction between nucleus and electrons is stronger in
chlorine atom // nuclei attraction towards electron is stronger in
chlorine atom
[r: is higher]
MARK
SUB
TOTAL
1
1
1
1
1
1
1
(ii)
1. Correct number of electrons and shell with nucleus
2. Label the charge and symbol of atom (can infer from nucleus)
(iii)
(d)
Ionic compound
[a : ionic]
[r : ionic bond]
Semiconductor// to produce microchips// to make concrete /
cement / ceramic/ pottery/ enamels
(e) (i)
Chemically inert // argon atom achieves stable octet electron
arrangement
(ii)
Volume of argon gas = 0.002 x 24 / / 0.048 dm3 / / 48 cm3
TOTAL
CONFIDENTIAL
2
9
NO.
3(a)
(b)
(c) (i)
(ii)
(d) (i)
(ii)
(e) (i)
(ii)
MARKING SCHEME
Ionic compound/substance that can conduct electricity in molten
state or aqueous solution and undergoes chemical changes.
K + , I- , H+ ,OHIodide ion and hydroxide ion
SUB
1
MARK
TOTAL
1
1
1
2I- I2 + 2e
(Colourless) gas bubbles releases
1
1
1. H+ ion is lower than K+ ion in the Electrochemical Series
2. H+ ion will be selectively discharged to form hydrogen
gas
Oxygen
1. No of mole = 24 / 24000 = 0.001 mol
2.
No of molecule = 0.001 x 6.02 x 1023 = 6.02 x 1020
TOTAL
CONFIDENTIAL
1
1
10
NO.
4(a)(i)
MARKING SCHEME
Copper(II) oxide
[a: copper oxide]
MARK
SUB
TOTAL
1
(ii)
Green
(iii)
Sodium carbonate / potassium carbonate/ ammonium carbonate
[a : formula]
(iv)
Na2CO3 + Cu (NO3)2 CuCO3 + 2 NaNO3
[based on answer in a(iii)]
(b)
(c)
1. Correct formulae of reactants and products
2. Balanced equation
1
1
1. Blue precipitate
2. Dissolves in excess ammonia solution
1
1
1. Add 2 cm3 dilute sulphuric acid followed by 2 cm3 of iron
( II) sulphate solution and shake
2. Concentrated sulphuric acid is added slowly/drop by drop
3. Brown ring is formed
TOTAL
CONFIDENTIAL
1
1
10
No.
5(a)
(b) (i)
(ii)
MARKING SCHEME
Volume of gas liberated // Mass of calcium carbonate
No of mole = 25 x 0.1 / 1000 = 0.0025 mol
MARK
SUB
TOTAL
1
1
1. 0.0025 mol HNO3 produce 0.00125 mol CO2
2. Volume of CO2 = 0.00125 x 24
= 0.03 dm3
Note : 1. [ecf from (b)(i)]
2. Point 2 must be correct with unit
1
1
1. Correct curves with label
2. Axis with label & units
1
1
(iv)
1. Rate of reaction of Exp II is higher than Exp I
(v)
1. Exp II has higher temperature than Exp. I
2. Kinetic energy of particles is higher.
3. Frequency of collision between H + and CaCO3 / CO32is higher
4. Frequency of effective collision is higher
1
1
1
(iii)
Volume of gas/ cm3
Isipadu gas / cm3
30 cm3
III
II
I
Time/ s
Masa /s
TOTAL
CONFIDENTIAL
11
NO
6 (a)
(b)
(c) (i)
MARKING SCHEME
To allow the movement of ions
Shown in the diagram (from electrode L to electrode M
through external circuit).
[r: answers in words]
Iron(III) ion / Ferum(III) ion / Iron(III) sulphate
[r: formula]
MARK
SUB
TOTAL
1
1
1
(ii)
Alternative 1
1. Add sodium hydroxide/ammonia solution.
2. Brown precipitate is formed.
1
1
3
Alternative 2
1. Add potassium hexacyanoferrate(II) solution.
2. Dark blue precipitate is formed.
Alternative 3
1. Add potassium thiocyanate solution.
2. Blood red colouration is formed.
(d)
Br2 + 2e 2Br-
(e)
1. Orange solution turns green
2. Cr2O72- ion undergoes reduction to form Cr3+ ion
1
1
Functional apparatus
Label apparatus and material
Label positive and negative terminal
TOTAL
1
1
1
(f)
CONFIDENTIAL
3
11
NO
7(a) (i)
MARKING SCHEME
P1. Empirical formula is (chemical) formula that shows the
simplest ratio of hydrogen and carbon atoms in benzene //
Formula that shows the simplest ratio of hydrogen to
carbon atoms in benzene is 1:1
P2. Molecular formula is (chemical) formula that shows the
actual number of hydrogen and carbon atoms in benzene//
Formula that shows the actual number of atoms which are
6 hydrogen and 6 carbon in benzene.
(ii)
ethanol,C2H5OH // water,H2O // magnesium oxide, MgO
[a: any compound where its empirical formula and molecular
formula is the same]
SUB
MARK
1
TOTAL
MARKS
1+1
(b) (i)
C
H
Element
80/12 = 6.67
20/1 = 20
Number of mole
6.67/6.67 = 1
20/6.67 = 3
Simplest ratio of
moles
Empirical formula of the compound is CH3
1
1
1
[CH3]n = 30
[12+3(1)]n = 30
n= 2
1
1
Max 4
Molecular formula of the compound is C2H6
(ii)
C2H6 + 7/2 O2 2CO2 + 3H2O
Correct formula of reactants and products
Balanced equation
1+1
(c) (i)
(ii)
Hydrocarbon
Homologous
series
alkane
alkene
General
formula
CnH2n+2
n=1,2..
CnH2n
n = 2,3,
Name
butane
But-2-ene
P1. J produces more soot than E.
P2 & P3. Calculation
E
J
4(12) x 100 = 82.76 4(12) x 100 = 85.71
% of carbon
58
56
% of carbon by mass in J is higher than E
TOTAL
CONFIDENTIAL
1+1
1
4
20
NO
EXPLANATION
SUB
MARK
TOTAL
MARKS
8 (a) (i)
Substance
Name
Specific
properties
(ii)
Q
Borosilicate glass
Withstand high
temperature//
Resistant to chemicals
//low thermal
expansion
Bronze
Shiny surface //
Does not corrode
easily//hard and
strong
1+1
1+1
P1& P2. Diagram
1+1
tin
Pure copper
copper
(b)
(i)
(ii)
Alloy P
P3. Alloy P/bronze is harder than pure copper
P4. Atomic size in pure copper is the same , atomic size in
alloy P/bronze is different.
P5. Atoms in pure copper are orderly arranged while atoms in
alloy P/bronze are not orderly arranged.
P6. When force is applied, layer of atoms in pure copper is
easier to slide than in alloy P/ bronze.
P1. Sulphur dioxide burnt/react with excess oxygen to produce
sulphur trioxide.
P2. Passed over vanadium(V) oxide catalyst at 450oC, 1 atm
P3. Chemical equation : 2SO2 + O2 2SO3
P1. Step 1: Sulphur trioxide is dissolved in concentrated
sulphuric acid to form oleum.
P2. SO3 + H2SO4 H2S2O7
P3. Step 2: Oleum is diluted with water to produce sulphuric
acid.
1
1
1
1
1
P4. H2S2O7 + H2O 2H2SO4
P1. Moles of S = 48 / 32 =1.5 mol
P2. 1 mol of S produce 1 mol SO2
Thus, 1.5 mol of S produce 1.5 mol SO2
P3.Volume of SO2 = 1.5 24 dm3 = 36 dm3
TOTAL
CONFIDENTIAL
1
1
1
(iii)
1
1
1
3
20
NO
9 (a) (i)
EXPLANATION
P1.Correct suggestion for solution T
Eg. Copper (II) sulphate solution /
Sodium chloride/ zinc sulphate solution /
sulphuric acid
P2. Correct suggestion for solution V
Eg. Glucose solution/benzene/ ethanol/methylbenzene
P3. Solution T has free moving ions.
P4. Solution V is made up of neutral molecules//
does not have free moving ions
(ii) P1. Zinc is more electropositive than copper.
P2. Zinc atom releases electron to form zinc ion Zn2+
P3. Half equation: Zn Zn2+ + 2e
P4. Electrons flow through external circuit to the copper
electrode
If T is copper(II) sulphate solution
P5. Copper(II) ion receives electron to form
copper atom
P6. Half equation: Cu2+ + 2e Cu
MARK
MARKS
1
1
1
1
1
1
1
1
1
OR
If T is sodium chloride solution / sulphuric acid
P5. Hydrogen ion receives electron to form hydrogen
P6. Half equation: 2H+ + 2e H2
(b)
P1. Materials : 2.0 mol dm-3 sodium hydroxide,
distilled water
P2. Apparatus : volumetric flask100 cm3, pipette 25 cm3,
[note : P1 & P2 can be inferred from procedure]
1
1
Calculation :
P3.
P4.
M1V1 = M2V2
2.0 x V1 = 0.5 x 100
V1 = 25 cm3
Procedure :
P5. Pipette 25 cm3 2.0 mol dm-3 of sodium hydroxide
solution.
P6. Transfer the solution into a volumetric flask.
P7. Add distilled water into the volumetric flask.
P8. until reaches the calibration mark.
P9. Close/ Put stopper on the volumetric flask.
P10.Shake the volumetric flask.
TOTAL
CONFIDENTIAL
10
1
1
1
1
1
1
1
1
10
20
NO
10
(a)(i)
EXPLANATION
P1. L : Mg / Magnesium
P2. R : Zn / Zinc
MARK
1
1
MARKS
[Note : 1. L must be more electropositive than R
2. Both L and R must be more electropositive than Cu]
P3. The heat of displacement for Experiment I is
higher than Experiment II.
P4. The distance between L / Cu is bigger/ further in the
Electrochemical Series // L is more electropositive
than R
(ii)
Mg + CuSO4 MgSO4 + Cu
P1. Correct chemical formula of reactant and product
P2. Balance chemical equation.
[adp metal L but should be more electropositive than Cu ]
P3. Number of mole of CuSO4 = 0.2 x 50 // 0.01
1000
P4. 1 mol of Cu displaced release 336000 J heat
P5. .: 0.01 mol of Cu 336000 J x 0.01 mol heat
1 mol
= 3360 J
(b)
P6. Change in temperature = 3360
50 X 4.2
= 16 oC
[ecf P5 from P3]
P1. Apparatus: Polystyrene cup , thermometer,
measuring cylinder ( suitable volume)
P2. Materials : [suitable salt solutions to produce
precipitate/any insoluble salt]
Eg. Lead(II) nitrate solution, sodium
sulphate solution
Procedure:
P3. Measure [25-200] cm3 of [0.1-2.0] mol dm-3 lead(II)
nitrate solution.
P4. Pour into a polystyrene cup.
P5. Measure [25-200] cm3 of [0.1-2.0] mol dm-3 sodium
sulphate solution.
P6. Pour into a different polystyrene cup.
P7. Measure the initial temperature of both solutions.
P8. Pour sodium sulphate solution quickly into lead(II)
nitrate solution.[a: vice versa]
P9. Stir the mixture.
P10. Record the highest temperature.[r: final temperature]
TOTAL
CONFIDENTIAL
11
1+1
1
1
1
1
1
1
1
1
1
1
1
1
10
20
MARKING GUIDELINES
SIJIL PENDIDIKAN MRSM
2014
PAPER 2
Symbol
//
()
[ ]
___ or bold
adp
wcr
a.
r.
ecf
/
CONFIDENTIAL
replace the whole sentence
replace the previous word
can be summarised from explanation
key word
avoid double penalty
wrong cancel right
accept
reject
error carry forward
or
12
