Chemistry 9701 · AS & A Level · Group 17

Group 17 — practice question

Chlorine may be made by the reaction below: $\text{MnO}_2(s) + 4\text{HCl}(aq) \rightarrow \text{MnCl}_2(aq) + 2\text{H}_2\text{O}(l) + \text{Cl}_2(g)$.
(a(i))[1]

Explain why $\text{MnO}_2(s)$ is called an oxidising agent in this reaction. Use oxidation numbers in your response.

(a(ii))[1]

State what you would see as this reaction takes place.

(b)[3]

The halogens chlorine, bromine and iodine are all volatile elements. State and explain how volatility changes down Group 17.

(c(i))[2]

Write an equation for the reaction of chlorine with cold aqueous sodium hydroxide, $\text{NaOH}$. Explain why it counts as a disproportionation reaction.

(c(ii))[1]

One product in the reaction of chlorine with hot aqueous sodium hydroxide is different from the products in (c)(i). Identify the compound formed in this reaction that is not formed in the reaction in (c)(i).

(d)[2]

State and explain how chlorine is used in water purification.

(e(i))[1]

Under certain conditions, chlorine undergoes a free-radical substitution reaction with ethane. State the conditions needed to start this reaction.

(e(ii))[1]

Write the overall equation for this free-radical substitution process.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: It changes chlorine from $-1$ to $0$ by oxidation

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