Page 18 - 1202 Question Bank Chemistry Form 5 KSSM

PAPER 2

Section A

Answer all questions.

1. The following flow chart shows the change of latex to vulcanised rubber through Steps I and II.

Step I Solid natural Step II Vulcanised
Latex
Acid rubber S Cl 2 rubber
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2
Diagram 1
(a) (i) Step I involves the coagulation of latex to form solid natural rubber. State how Step I is carried out
in the laboratory. [1 mark]

(ii) State two properties of natural rubber. [2 marks]

(b) Step II involves the vulcanisation of rubber. State how Step II is carried out. [3 marks]

(c) (i) Draw the structural formulae of unvulcanised rubber and vulcanised rubber. [2 marks]

Unvulcanised rubber Vulcanised rubber

(ii) Based on the structural formula in (c)(i), state the structural change that takes place when natural
rubber is vulcanised. [2 marks]

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Question 1:
(c) (i) Sulphur cross linkages are found in vulcanised rubber.
(c) (ii) Double bonds between carbon atoms in rubber molecule react with sulphur. SOS TIP