Chemistry 9701 · AS & A Level · Halogen compounds

Halogen compounds — practice question

(a) A bottle without a label contains the straight-chain halogenoalkane Q. The molecular formula of Q is $\text{C}_5\text{H}_{11}X$, where $X$ is a halogen; bromine, chlorine or iodine. A test is used to identify which halogen is in Q. A portion of Q is added to NaOH(aq) and heated. Dilute nitric acid is then added, followed by a few drops of aqueous silver nitrate. A cream precipitate forms.
(a(i))[1]

Suggest which halogen X is.

(a(ii))[1]

Write an ionic equation for the formation of the cream precipitate. Include state symbols.

(a(iii))[2]

Describe one more test that would verify the identity of X. Give both the test and the outcome expected.

(b(i))[1]

Suggest the structural formula for Q, the straight-chain halogenoalkane.

(b(ii))[2]

Explain why the reaction is more likely to follow an $S_N2$ mechanism than an $S_N1$ mechanism.

(c)

Two different halogenoalkanes, P and R, both with molecular formula $\text{C}_4\text{H}_9\text{Cl}$, are each dissolved in ethanol and heated under reflux with sodium hydroxide separately. The main organic product in both reactions is methylpropene.

(c(i))[1]

Name the reaction type occurring.

(c(ii))[1]

Write an equation, using molecular formulae, that represents the reaction taking place.

(c(iii))[1]

Draw the skeletal formula for methylpropene.

(c(iv))[2]

Give the names assigned to P and R.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Br / Bromine” …

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