Alkanes (Edexcel International AS Chemistry): Exam Questions

Heptane, C₇H₁₆ , is an alkane found in crude oil.

Heptane can undergo incomplete combustion.

i) Give a reason why incomplete combustion sometimes occurs.

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i) Write the equation for the incomplete combustion of heptane, forming carbon monoxide and water as the only products. State symbols are not required.

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Heptane is reformed into branched-chain and cyclic hydrocarbons that are used in petrol.

i) Draw the skeletal formulae of a branched-chain alkane and a cycloalkane, each containing seven carbon atoms.

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ii) Write the equation for the reforming of heptane into a cycloalkane.

Use molecular formulae.

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iii) Give a reason for adding cycloalkanes to petrol.

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Heptane, C₇H₁₆ , reacts with chlorine in the presence of ultraviolet radiation.

i) State the type and mechanism of this reaction.

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ii) Give the mechanism for the reaction to produce C₇H₁₅Cl, C₁₄H₃₀ and HCl as the only products.

Include the name of each of the steps in your mechanism.
Curly half-arrows are not required.

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