Chemistry 9701 · AS & A Level · The Periodic Table: chemical periodicity

The Periodic Table: chemical periodicity — practice question

Period 3 elements react with chlorine gas, $\text{Cl}_2(\text{g})$, to make chlorides. The table compares the different observations seen when two Period 3 chlorides are added to water.
(a(i))[1]

Write an equation for the reaction that takes place when $\text{SiCl}_4$ is added to cold water. Include state symbols.

(a(ii))[1]

Name the type of reaction that occurs when $\text{SiCl}_4$ is added to water. Do not consider whether the reaction is exothermic or endothermic.

(a(iii))[2]

Explain, in terms of bonding, why $\text{NaCl}$ and $\text{SiCl}_4$ behave differently when they are added to water.

(a(iv))[3]

Explain, in terms of electronegativity, why the bonding in $\text{NaCl}$ is different from the bonding in $\text{SiCl}_4$.

(b(i))[2]

In the reaction $\text{Cl}_2 + \text{H}_2\text{O} \rightarrow \text{HCl} + \text{HClO}$, identify the oxidation number of chlorine in each chlorine-containing species.

(b(ii))[1]

Name the type of reaction that occurs.

(b(iii))[1]

Explain why chlorine is used in water purification.

(c)[2]

A mixture of $\text{HCl}$ and $\text{HClO}$ is added to cold dilute $\text{NaOH}$. One of the products acts as a bleach. Suggest the equation for the reaction that takes place.

Worked solution & mark scheme

This 13-mark question has a full step-by-step worked solution and mark scheme. One marking point: Balanced equation: $SiCl_4(l) + 2H_2O(l) \rightarrow SiO_2(s) + 4HCl(aq/g)$ with the correct state symbols.

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