Page 60 - ACE YR IGCSE A TOP APPROACH TO CHEM

(b) It contains C, H and O [1] 11 (a) Condensation [1]
the ratio is 1 : 2 : 1 [1]
(b) O O
(c) O O O C C O O

Correct C–O linkage [1] Correct ester linkage [1]
Draw the arm to show continuous [1] Draw the arm to show continuous [1]
Three repeat units [1] (c) Polyester is formed from dicarboxylic acid and
(d) Water [1] diol monomers. [1]
An ester is formed from monomers with only
(e) Hydrolysis [1] one side carboxyl group and hydroxyl group. [1]

(f) Use paper chromatography [1] (d) Any two from: [2]
Use a locating agent [1] • Disposal in landfill sites
Calculate R value [1] • Accumulation in oceans
f
(g) (i) 2C H OH [1] + 2CO [1] • Formation of toxic gases from burning
2
5
2
Balanced equation [1]
(ii) Without the presence of oxygen [1] 12 Experimental Techniques and Chemical
(iii) Fractional distillation [1] Analysis
Part 1: Multiple-choice Questions
10 (a) They contain carbon and hydrogen [1]
only [1] 1 D
To measure the volumes of two solutions, a pipette
(b) Contain all C-C single bonds [1] is needed. To check if the reaction gives out heat, a
(c) (i) A hydrogen atom is replaced by a halogen thermometer is needed.
atom. [1] 2 B
(ii) UV light [1] D is for titration, C is for filtering away the charcoal, and
(iii) CH CH + Br ➞ CH CH Br [1] + HBr [1] A is for crystallisation.
3
3
3
2
2
(d) (i) Only one product is formed [1] 3 A
A pipette has a smaller diameter. It measures the volume
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H
H
(ii)
H
more accurately compared to a beaker.
H C C C H 4 D
[1] Condenser is used to condense / cool down the water
H Br Br
vapour to water.
(e) H H H H 5 C
Gas Z is denser than air. It cannot move upward.
H C C C C H
6 C
H H [1] If the boiling points of both liquids are below room
But-2-ene [1] temperature, it will exist in gaseous state.
(f) (i) Poly(ethene) [1] 7 A
(ii) First, filter away the copper from the mixture because
H H copper is a solid. Then, heat it to evaporate the excess
water until it reaches its crystallisation point. Lastly, let it
C C cool down and dry to form crystals.
H H n 8 C
Spots 2, 3 and 4 have the same positions as the spots in
Correct monomer [1] the mixture.
Draw the arm to show continuous [1]
9 C
(g) O H O H O H The locating agent is sprayed to visualise the spot as it
can turn the colourless spot into the coloured spot.
C N C N C N 10 A
Correct linkages [1] Water will dissolve the HCl. Concentrated sulfuric acid is
for dehydration. Water will be absorbed.
Draw the arm to show continuous [1]
11 B
(h) Ethanol [1] Na gives a yellow flame. Li gives a red flame. Ca gives
2+
+
+
Butanoic acid [1] an orange-red flame.

Cambridge IGCSE TM
172 Ace Your Chemistry

Answers.indd 172 3/4/22 3:54 PM