Cambridge International AS Level Chemistry Answers to self-assessment questions

Answers to SAQs
Chapter 14 iii H H H H H H H H

H C C C C C C C C H
1a i Find out the ratio of moles:
H H H H H
C:H
72 : 0.18 H C H H C HH C H
12 1.0
= 0.06 : 0.18 H H H
Simplest whole number ratio is:
b 3-ethyl-3-methylheptane
1:3
so empirical formula is CH3 5 a H H H
ii C2H6
C C C H
b C2H4O2
H H H
2 a H H
b H H H
C C
H C C C H
H H
H H H
b H H H
c H
H C C C H
H C H
H H H
H C H

3 a
H H H H
b octane = CH3CH2CH2CH2CH2CH2CH2CH3
H C C C C H
2,2,4-trimethylpentane =
octane = CH3CH2CH2CH2CH2CH2CH2CH3
CH
2,2,4-trimethylpentane 3C(CH
= CH3C(CH )2CH2CH(CH
3)2CH32CH(CH3)CH3 3
)CH3 H H H H
cyclohexane
cyclohexane = = H H
CH2
6 a H H
CH2 CH2 H C H
H C C C H
CH2 CH2
C C
CH2
H H H H
4 a i H H H H H

H C H b H H

H H H H C C H
H
H C C C H
H C C C C H
H C
H H H H
H H
ii H H H H H H H H H

H C C C C C C C H 7 a 1,2-dibromopropane, 1,3-dibromopropane,
1,1-dibromopropane, 2,2-dibromopropane
H H H H H

H C H H C H

H C H H C H

H H

Cambridge International AS and A Level Chemistry © Cambridge University Press 2014

b Cl H H H Cl H b H H

H C C C H H C C C H C C

H H H H H H F Cl Cl F
Br Br
1-chloropropane 2-chloropropane

8 a i H H
O
11 a Cl2 → Cl• + Cl•
or Cl2 → 2Cl•
H C C C

H
b H H
H H
propanal H C Cl H C+ + Cl–

ii H O H H H

H C C C H c OH–
d OH– has lone pairs of electrons on its oxygen
H H
propanone atom whereas H2 and H+ have no available
lone pairs of electrons.
b H
e H+
H O H
f H+ can accept a pair of electrons, whereas H2
H C C C H and OH– cannot.
H H H g Option B, because in this tertiary carbocation
propan-2-ol there are three alkyl groups, each tending to
donate electrons to the positively charged
9 H H H H H H H H H carbon atom, reducing its charge density
and making the ion energetically more stable
H C C C C C H H C C C C H
than the primary (option C) or secondary
H H H H H H H H (option A) carbocations.
H C H
pentane
12 a hydrolysis
H
b reduction
H
methylbutane c elimination
H C H
d addition
H H
e (free-radical) substitution
H C C C H

H H

H C H

dimethylpropane

10 a H H H

H C C H H C H

C C H C C
H H H
H H H C H

H
cis-but-2-ene trans-but-2-ene

Cambridge International AS and A Level Chemistry © Cambridge University Press 2014