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CAMBRIDGE INTERNATIONAL EXAMINATIONS
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Cambridge International Advanced Subsidiary and Advanced Level
MARK SCHEME for the October/November 2014 series
9701 CHEMISTRY
9701/23
Paper 2 (AS Structured Questions), maximum raw mark 60
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of
the examination. It shows the basis on which Examiners were instructed to award marks. It does not
indicate the details of the discussions that took place at an Examiners’ meeting before marking began,
which would have considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner
Report for Teachers.
Cambridge will not enter into discussions about these mark schemes.
Cambridge is publishing the mark schemes for the October/November 2014 series for
most Cambridge IGCSE®, Cambridge International A and AS Level components and some
Cambridge O Level components.
® IGCSE is the registered trademark of Cambridge International Examinations.
Page 2
Question
1
Mark Scheme
Cambridge International AS/A Level – October/November 2014
Syllabus
9701
Mark Scheme
Marks
(a) (i) increasing distance of (outer/highest energy) electron(s) from nucleus
OR increasing distance of outer/valence shell from nucleus
(c) (i)
1
reduces attraction
1
1
(boiling point) increases (down the group)
1
increasing number of electrons (in molecules) down group
1
increasing strength of / more van der Waals’ forces (allow correct alternatives to van der Waals’ forces)
1
so more energy needed to overcome (the forces)
1
I
57.2
127
2.253
0.450
0.450
0.450
5
1
[3]
1
increase in attraction
F
42.8
19
Total
1
increased shielding / screening (from inner shells)
(ii) increasing cation charge / effective nuclear charge
OR decreasing number of electrons compared with protons
(b)
Paper
23
[2]
[4]
1
/ IF5
1
1
EF = MF or IF5= 222
© Cambridge International Examinations 2014
[3]
Page 3
Mark Scheme
Cambridge International AS/A Level – October/November 2014
Syllabus
9701
Paper
23
(ii)
xx
x
x
xCl
xx
1
I
1
[2]
1
1
1
1
[4]
(ii) 3Cl2 + 6NaOH 5NaCl + NaClO3 + 3H2O
M1: correct species
M2: balanced equation
1
1
[2]
(iii) 0 to –1
(0 to) +5
1
1
[2]
(Yes) as electronegativities are different
(d) (i) W = NaClO;
X = NaClO3;
Y = HCl;
Z = AgCl
(iv) Ag+(aq) + Cl –(aq) AgCl(s)
[1]
[23]
© Cambridge International Examinations 2014
Page 4
Question
Mark Scheme
2
(a)
(b)
Mark Scheme
Cambridge International AS/A Level – October/November 2014
Syllabus
9701
Paper
23
Marks
Total
CH4 + H2O CO + 3H2
1
[1]
Label on graph indicating catalysed and uncatalysed Ea
OR statement Ea catalysed is lower (than Ea uncatalysed) owtte
1
Reference to catalyst creating alternative mechanism / reaction pathway / route
1
Idea that more molecules have sufficient energy (to react)
1
so greater chance / frequency of successful collisions
1
(c)
N
1
H
H
H
angle = 107o
shape = (trigonal) pyramid(al)
1
1
(d) (i) Advantage = higher rate
Greater Kinetic Energy / speed / collision frequency / proportion of successful collisions
(ii)
[4]
[3]
1
1
Disadvantage – reduced yield / less product / more reactants
1
(Forward reaction) exothermic AND (hence in accordance with Le Chatelier’s Principle) equilibrium / reaction
shifts left (to counteract increasing temp) ora
1
[4]
1
[1]
Kp =
2
pNH3
3
pN2 × pH2
© Cambridge International Examinations 2014
Page 5
(iii)
N2(g) +
2
(–0.8)
1.2
Mark Scheme
Cambridge International AS/A Level – October/November 2014
3H2(g) 3
(–1.6×3/2)
0.6
Paper
23
2NH3(g)
0
1
1.60
xNH3 = 1.6/3.4 (= 0.471)
xN2 = 1.2/3.4 (= 0.353)
xH2 = 0.6/3.4 (= 0.176)
Kp =
Syllabus
9701
1
0.4712 × (2 × 107)2
= 2.88 × 10–13 Pa–2
7
3
7 3
0.353 × 2 × 10 × 0.176 × (2 × 10 )
1+1
[5]
[18]
© Cambridge International Examinations 2014
Page 6
Mark Scheme
Cambridge International AS/A Level – October/November 2014
Question
Mark Scheme
3
P: CH3CH2CH2CH=CH2
Q: CH3CH2CH=CHCH3
R: CH3CH2C(CH3)=CH2
S: CH3CH=C(CH3)2
T: CH3CH2COCH3
(a)
(b) (i) (Different molecules with the) same (molecular and) structural formula
different arrangements of atoms (in space)
(ii)
H
H
C
H
H
H
C
H
C
H
H
C
H
trans-pent-2-ene
(c)
H
H
C
C
H
H
H
C
HH
C
H
Syllabus
9701
Paper
23
Marks
Total
1
1
1
1
1
[5]
1
1
[2]
H
C
C
H
1
H
cis-pent-2-ene
butan-2-ol
1
[2]
1
[1]
[10]
© Cambridge International Examinations 2014
Page 7
Mark Scheme
Cambridge International AS/A Level – October/November 2014
Syllabus
9701
Paper
23
Question
Mark Scheme
4
reagent = conc H2SO4 or conc H3PO4
1
conditions = heat
1
(a)
OR
Marks
pass vapour over hot Al2O3
“reagent”
“conditions”
[2]
(b) (i) C3H7OH + 2[O] C2H5CO2H + H2O
1
(ii) reagent = sodium / potassium dichromate or correct formula
(c)
(d)
Total
[1]
1
conditions = H+ / acidified and (heat under) reflux
1
[2]
U = CH3CH(OH)CH3
V = CH3CHBrCH3
1
1
[2]
OR
U = CH3CH2CH2OH
V = CH3CH2CH2Br
reagent = KOH / NaOH
1
conditions = ethanol / alcohol AND Heat / reflux
1
[2]
[9]
© Cambridge International Examinations 2014