Chemistry 9701 · AS & A Level · Hydrocarbons

Hydrocarbons — practice question

But-2-ene, $\text{CH}_3\text{CH}=\text{CHCH}_3$, is a useful compound produced when hydrocarbons in crude oil are cracked.
(a)[2]

Give two separate conditions under which long chain hydrocarbons can be cracked.

(b)[1]

Dodecane, $\text{C}_{12}\text{H}_{26}$, is a long chain hydrocarbon found in crude oil and may be cracked to produce but-2-ene and an alkane. Write a balanced equation for this reaction.

(c)[4]

The reactions of but-2-ene are shown. In the boxes below, write the structural formulae of organic compounds A to D.

(d(i))

Draw the skeletal formula for compound D.

(d(ii))[3]

Using the letters A to D where relevant, identify the compounds that are chiral. If there are none, write "none".

(e)[1]

But-2-ene can undergo polymerisation to produce poly(butene). Draw the structural formula of part of the poly(butene) chain showing two repeat units.

(f(i))

Compound C is a liquid that can be treated with concentrated sulfuric acid to form a gas, E, which will decolourise aqueous bromine when bubbled through it. Suggest the structural formula of E.

(f(ii))

Suggest the structural formula of the product formed when E reacts with excess bromine.

(f(iii))[3]

Identify the type of reaction that occurs between E and an excess of bromine.

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