Chemistry 9701 · AS & A Level · Chemistry of transition elements
Chemistry of transition elements — practice question
Chromyl chloride, $\text{CrO}_2\text{Cl}_2$, is made by warming a mixture of potassium dichromate(VI) and potassium chloride with concentrated sulfuric acid. $\text{K}_2\text{Cr}_2\text{O}_7 + 4\text{KCl} + 3\text{H}_2\text{SO}_4 \rightarrow 2\text{CrO}_2\text{Cl}_2 + 3\text{K}_2\text{SO}_4 + 3\text{H}_2\text{O}$.
(a)[2]
Use the data below to complete the Hess’ Law cycle and determine the reaction enthalpy, $\Delta H_r$.
(b(i))[1]
Suggest the type of isomerism exhibited by these complex ions.
(b(ii))[4]
Explain why these two complex ions are coloured, and why their colours are different.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Accurate Hess cycle calculation that gives $\Delta H = -81\,\text{kJ mol}^{-1}$” …