Page 53 - Spotlight A+ Form 4 & 5 Chemistry KSSM

Section C

[20 marks]
Answer the question.
11. (a) Liquid of compounds Q and R are hydrocarbons. An experiment is carried out to investigate the
quantity of soot produced when compounds Q and R are burnt in oxygen. The results are shown in
Table 11.1

Compound Q Compound R
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Burn in the air producing yellow sooty flame. Burn in the air producing yellow and more sooty flame.
Table 11.1
(i) State the general formula of compound Q. [1 mark]
(ii) Explain the differences in the observations of the combustion of compounds Q and R by
comparing the percentage of carbon by mass. [3 marks]
[Relative molecular mass: Q = 86; R = 84; Relative atomic mass C = 12]
(b) Table 11.2 shows the properties of four organic compounds. Each compound has three carbon atoms
per molecule.

Organic
compound Properties

Miscible with water in all proportions. Burns with blue flame to form carbon
V
dioxide, CO and water, H O.
2
2
Soluble in water, H O. Reacts with calcium carbonate, CaCO to produce carbon
W 2 3
dioxide gas, CO .
2 SPM MODEL PAPER
Insoluble in water, H O. Decolourise the orange colour of acidified potassium
X 2
dichromate(VI), K Cr O solution.
8
2
2
Y Insoluble in water, H O. Sweet smell.
2
Table 11.2
Reffering to Table 11.2, state each of the following:
(i) Name of the homologues series for compounds V, W, X and Y. [4 marks]
(ii) Functional group of compound V and X. [2 marks]
(c) Figure 11.1 shows the structural formulae of hydrocarbon A and hydrocarbon B. Both hydrocarbons
have different chemical properties.

H H H H H H H H H H H H H H

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

H H H H H H H H H H H H
Hydrocarbon A Hydrocarbon B
Figure 11.1
(i) Draw structural formula for two isomers of hydrocarbon A. [2 marks]
(ii) Describe a laboratory experiment to differentiate both hydrocarbons. In your description,
include the following:
• Procedure
• Observations
• Chemical equation involved [8 marks]

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