Q1.   Crude oil is a mixture of a large number of compounds most of which are hydrocarbons such as the molecule shown below.

(a)     What is a hydrocarbon?
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(1)
(b)     What is the chemical formula of the molecule shown above?
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(1)
(c)     The cracking of large molecules obtained from crude oil is one of the important processes in an oil refinery. Cracking involves the thermal decomposition of large molecules. The diagram below shows an apparatus that can be used to demonstrate cracking in the laboratory. The porous pot acts as a catalyst in the reaction.

(i)      What happens during thermal decomposition?
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(2)
(ii)     What effect does the porous pot catalyst have on the reaction?
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(1)
(iii)     Complete the equation below for the cracking of the molecule. C20H42.
C20H42  →  C12H26  +  ............................................
(1)

M1.          (a)     A compound made from carbon and hydrogen (not mixture etc.)
1
(b)     C5H12
1

(c)     (i)      Break down
by heat
(ii)     Speeds up reaction
(iii)     C8H16
each for 1 mark
4
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