Page 57 - ACE YR IGCSE A TOP APPROACH TO CHEM

(ii) UV light [1] (d) (i) A process of making a long chain of
Provide the activation energy [1] organic compound [1]
by using one type of monomer [1]
(iii) Chloroethane / dichloroethane /
trichloroethane / tetrachloroethane / (ii) H H
pentachloroethane / hexachloroethane [1]
ClCH CH / ClCH CH Cl / any correct C C
2
2
3
2
number of chlorine atom according to the H H n
named molecule [1]
Note: The question requires the candidate to Correct monomer [1]
write the molecular structure. If the word used Draw the arm to show continuous [1]
is ‘draw’, the candidate should draw as below: Step 1: Draw the structure of ethene but
H H change the C=C double bond to a single bond.
Step 2: Draw the arm at the side of both
Cl C C H carbon atoms.
Step 3: Add brackets and a “n” at the bottom
H H right.
This is an example of a drawn structure. (iii) Polyethene [1]
(e) (i) CH CH CH + 5O ➞ 3CO + 4H O (e) (i) They have the same molecular formula [1]
2
2
2
3
3
2
Correct formula [1] different structural formula [1]
Balanced equation [1] (ii) H H H H H
(ii) Global warming [1]
Carbon dioxide is a greenhouse gas that causes H C C C C C H
global warming. H H H [1]
3 (a) Contains a C=C double bond [1] Tips: Move the functional group which is the
The C=C double bond allows the addition reaction C=C double bond to different locations.
to happen. (f) C H + C H [2]
4
4
10
2
(b) Only one product is formed [1] or
(c) (i) Ethane [1] C H + C H [2]
6
8
3
3
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[1]
The products of cracking include alkanes and
C H
2 6
alkenes.
H H H H Always ensure the total number of carbon and
hydrogen atoms in the products is the same as the
C C + H H H C C H
reactant.
H H H H 4 (a) (i) Fermentation [1]
Nickel [1] (ii) Yeast [1]
(ii) Ethanol [1] 25°C [1]
CH CH OH [1] Yeast is used to catalyse the reaction in the
3 2 absence of air.
H H H H The high temperature used will denature the
yeast.
C C + H O H H C C O H
(iii) High percentage of ethanol [1]
H H H H When the percentage of ethanol reaches a
certain level, the yeast will be denatured.
Phosphoric acid [1]
(b) (i) Adding water [1]
(iii) Dibromoethane [1]
(ii) C H + H O ➞ C H OH
H H H H 2 4 2 2 5
Correct reactants [1]
C C + Br Br Br C C Br Correct product [1]
H H H H [1] (iii) 300°C [1]
60 atm / 6000 kPa [1]
H H H H Phosphoric acid [1]
C C + Br Br Br C C Br (c) Biological method
Advantage [1]
H H H H • Use of renewable resources
UV light [1] Maize or sugarcane is used in fermentation.
These plants can be planted again and again.

Answers 169

Answers.indd 169 3/4/22 3:54 PM