State an ionic equation, including state symbols, for the reaction taking place when an aqueous solution containing chloride ions is added to an aqueous solution containing lead(II) ions.

The solubility product, \({K_{{\text{sp}}}}\), of lead(II) chloride is \(1.7 \times {10^{ - 5}}\) at 298 K. Determine the concentration of lead(II) ions, in \({\text{mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\), when equal volumes of \({\text{1.0 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\) aqueous potassium chloride and a solution of \({\text{0.50 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\) lead(II) ions are mixed.

State any assumption used.

\({\text{P}}{{\text{b}}^{2 + }}{\text{(aq)}} + {\text{2C}}{{\text{l}}^ - }{\text{(aq)}} \rightleftharpoons {\text{PbC}}{{\text{l}}_2}{\text{(s)}}\)

correct reactant ions and product;

correct state symbols;

Do not penalize if equilibrium sign is not given.

\({K_{{\text{sp}}}} = {\text{[P}}{{\text{b}}^{2 + }}{\text{(aq)][C}}{{\text{l}}^ - }{\text{(aq)}}{{\text{]}}^2} = {\text{1.7}} \times {\text{1}}{{\text{0}}^{ - 5}}\);

Assumption: \({\text{[PbC}}{{\text{l}}_2}{\text{(s)]}} = {\text{1}}\) / concentration of a solid is a constant (incorporated into \({K_{{\text{sp}}}}\));

\({\text{[C}}{{\text{l}}^ - }{\text{]}} = {\text{2[P}}{{\text{b}}^{2 + }}{\text{]}}/{\text{1.7}} \times {\text{1}}{{\text{0}}^{ - 5}} = {\text{[P}}{{\text{b}}^{2 + }}{\text{][C}}{{\text{l}}^ - }{{\text{]}}^{\text{2}}} = 4{x^3}\);

\({\text{[P}}{{\text{b}}^{2 + }}{\text{(aq)]}} = 1.6 \times {10^{ - 2}}/0.016{\text{ (mol}}\,{\text{d}}{{\text{m}}^{ - 3}}{\text{)}}\);

Ignore state symbols.

Award [3] for correct final numerical answer if assumption is not stated or is incorrect.

The ionic equation for the precipitation of lead(II) chloride in Q19 was well done but there were few correct calculations and the assumption was poorly understood. This question is based on E.12.1.

The ionic equation for the precipitation of lead(II) chloride in Q19 was well done but there were few correct calculations and the assumption was poorly understood. This question is based on E.12.1.