Explain why the solubility of the Group 2 sulfates falls down the group.
Describe the observations seen when magnesium and barium are each reacted separately with an excess of dilute sulfuric acid.
The solubility product, $K_{sp}$, for $\text{BaSO}_4$ is $1.08 \times 10^{-10}\ \text{mol}^2\,\text{dm}^{-6}$ at $298\,\text{K}$. Calculate the solubility of $\text{BaSO}_4$ in g per $100\,\text{cm}^3$ of solution.
The equation for producing a gaseous sulfate ion is given. $\text{S(s)} + 2\text{O}_2\text{(g)} + 2\text{e}^- \rightarrow \text{SO}_4^{2-}\text{(g)}\quad \Delta H = \Delta H_f^\circ\ \text{of } \text{SO}_4^{2-}\text{(g)}$. Calculate the standard enthalpy change of formation, $\Delta H_f^\circ$, of $\text{SO}_4^{2-}\text{(g)}$. Drawing a labelled energy cycle may help. Use the appropriate data from Table 1.1 in your working.
Suggest the difference between the lattice energy of $\text{BaSO}_4\text{(s)}$ and the lattice energy of $\text{Cs}_2\text{SO}_4\text{(s)}$. Explain your answer.
The reaction between solid hydrated barium hydroxide, $\text{Ba(OH)}_2\cdot 8\text{H}_2\text{O}$, and ammonium salts is endothermic. Calculate the minimum temperature at which the reaction of $\text{Ba(OH)}_2\cdot 8\text{H}_2\text{O}$ with $\text{NH}_4\text{NO}_3$ becomes feasible. Show all your working. $\text{Ba(OH)}_2\cdot 8\text{H}_2\text{O(s)} + 2\text{NH}_4\text{NO}_3\text{(s)} \rightarrow 2\text{NH}_3\text{(g)} + \text{Ba(NO}_3)_2\text{(s)} + 10\text{H}_2\text{O(l)}\quad \Delta H_r^\circ = +132\,\text{kJ mol}^{-1},\ \Delta S^\circ = +616\,\text{J K}^{-1}\text{ mol}^{-1}$
When solid barium hydroxide and ammonium chloride are mixed, the reaction goes ahead readily at room temperature. $\text{Ba(OH)}_2\cdot 8\text{H}_2\text{O(s)} + 2\text{NH}_4\text{Cl(s)} \rightarrow 2\text{NH}_3\text{(g)} + \text{BaCl}_2\cdot 2\text{H}_2\text{O(s)} + 8\text{H}_2\text{O(l)}\quad \Delta H_r^\circ = +133\,\text{kJ mol}^{-1}$. Table 1.2 provides some relevant standard entropies. Calculate the standard Gibbs free energy change, $\Delta G^\circ$, for this reaction at $25^\circ\text{C}$.
The reaction between solid hydrated barium hydroxide, $\text{Ba(OH)}_2\cdot8\text{H}_2\text{O}$, and ammonium salts absorbs heat.