Chemistry 9701 · AS & A Level · Group 17

Group 17 — practice question

The halogens chlorine, bromine and iodine display patterns in chemical and physical properties down the group. Table 3.1 gives some properties of chlorine, bromine and iodine.
(a(i))[1]

Complete Table 3.1.

(a(ii))[2]

The bond energy values in Table 3.1 are for the $X$-$X$ bond, where $X$ stands for the halogen. Explain the pattern in the strength of the $X$-$X$ bond in the halogens.

(b)[2]

Explain, using an equation, how chlorine, $\text{Cl}_2$, is used in water purification. State the function of the active species produced.

(c(i))[1]

Identify the sodium halide that reacts with concentrated $\text{H}_2\text{SO}_4$ to produce $\text{H}_2\text{S}$.

(c(ii))[1]

Identify the sodium halide that undergoes only a Brønsted-Lowry acid-base reaction with concentrated $\text{H}_2\text{SO}_4$.

(c(iii))[1]

A student adds a few drops of $\text{AgNO}_3\text{(aq)}$ to a solution of $\text{NaBr(aq)}$. State what you see.

(d(i))[1]

Identify every intermolecular force present between molecules of $\text{IBr}$.

(d(ii))[1]

Name the mechanism involved in the reaction of $\text{IBr}$ with propene.

(d(iii))[2]

The reaction of $\text{IBr}$ with propene gives two structural isomers. Draw the two structural isomers shown by these molecules.

(d(iv))[1]

Identify the type of structural isomerism shown by the molecules in (d)(iii).

(d(v))[2]

Explain why the two structural isomers do not form in equal amounts.

Worked solution & mark scheme

This 15-mark question has a full step-by-step worked solution and mark scheme. One marking point: Bromine appears as a dark red-brown liquid, whereas iodine is a grey/black solid.

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