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

The Periodic Table: chemical periodicity — practice question

The list below shows some of the common chlorides of Period 3 elements. $\text{NaCl}$, $\text{MgCl}_2$, $\text{AlCl}_3$, $\text{SiCl}_4$, $\text{PCl}_5$
(a(i))[1]

From this list, identify all the chlorides that possess giant ionic structures in the solid state.

(a(ii))[1]

From this list, identify all the chlorides that react vigorously with water to produce strongly acidic solutions.

(a(iii))[1]

From this list, identify the chloride that dissolves in water to give a neutral solution.

(a(iv))[1]

From this list, identify the chloride formed from the element with the highest melting point.

(b)[1]

$\text{NaCl}$ is one product of the reaction of chlorine gas and cold aqueous sodium hydroxide. Identify the other products.

(c(i))[1]

$\text{PCl}_5$ reacts with alcohols to form chloroalkanes. Identify this type of reaction.

(c(ii))[1]

Draw the structure of the organic product formed in the reaction of an excess of $\text{PCl}_5$ with butane-1,3-diol.

(d(i))[2]

Sulfur, $\text{S}_8$, reacts with chlorine to produce a range of chlorides. The main ones are $\text{S}_2\text{Cl}_2$ and $\text{SCl}_2$. $\text{SCl}_2$ is formed when sulfur reacts with excess chlorine. reaction 1: $\text{S}_8\text{(s)} + 4\text{Cl}_2\text{(g)} \rightarrow 4\text{S}_2\text{Cl}_2\text{(l)} \quad \Delta H_r = -58.2\,\text{kJ mol}^{-1}$ reaction 2: $\text{S}_2\text{Cl}_2\text{(l)} + \text{Cl}_2\text{(g)} \rightleftharpoons 2\text{SCl}_2\text{(l)} \quad \Delta H_r = -40.6\,\text{kJ mol}^{-1}$ $\text{SCl}_2$ is a cherry-red liquid that reacts vigorously with water to form an acidic solution. Use this information to deduce the bonding and structure shown by $\text{SCl}_2$. Explain your answer.

(d(ii))[2]

Calculate the enthalpy change of formation, $\Delta H_f$, of $\text{SCl}_2\text{(l)}$. You may find it useful to use Hess’s Law to construct an energy cycle. enthalpy change of formation of $\text{SCl}_2\text{(l)}$, $\Delta H_f = \ldots\ldots\ldots\ldots\ldots\ldots\ldots\ldots\, \text{kJ mol}^{-1}$

(d(iii))[1]

State the effect of a decrease in pressure on the position of equilibrium in reaction 2. Explain your answer.

(d(iv))[2]

Define the term structural isomer.

(d(v))[2]

Suggest a value for the $\text{Cl}$-$\text{S}$-$\text{S}$ bond angle in isomer I. Explain your answer. bond angle = \dots\dots\dots\dots\dots\dots\dots\dots$^\circ$

(d(vi))[2]

Draw a dot-and-cross diagram to show the bonding in isomer II. Show outer shell electrons only.

Worked solution & mark scheme

This 18-mark question has a full step-by-step worked solution and mark scheme. One marking point: $\mathrm{NaCl}$ and $\mathrm{MgCl}_2$.

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