The solubility of the Group 2 sulfates falls as you go down the group. Explain this trend.
Describe what is observed when magnesium and barium are reacted separately with an excess of dilute sulfuric acid.
The solubility product, $K_{sp}$, for barium sulfate is $1.08 \times 10^{-10}\ \text{mol}^2\text{dm}^{-6}$ at $298\,\text{K}$. Calculate the solubility of barium sulfate in $\text{g}$ per $100\,\text{cm}^3$ of solution.
The equation showing the formation of a gaseous sulfate ion is shown. $\text{S}(s) + 2\text{O}_2(g) + 2e^- \rightarrow \text{SO}_4^{2-}(g)$. Calculate the standard enthalpy change of formation, $\Delta H_f^\circ$, of $\text{SO}_4^{2-}(g)$. Drawing a labelled energy cycle may help. Use relevant data from Table 1.1 in your calculation.
Suggest how the lattice energy of $\text{BaSO}_4(s)$ compares with the lattice energy of $\text{Cs}_2\text{SO}_4(s)$. 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. $\text{Ba(OH)}_2\cdot 8\text{H}_2\text{O}(s) + 2\text{NH}_4\text{NO}_3(s) \rightarrow 2\text{NH}_3(g) + \text{Ba(NO}_3)_2(s) + 10\text{H}_2\text{O}(l)$, $\Delta H_r^\circ = +132\,\text{kJ mol}^{-1}$, $\Delta S^\circ = +616\,\text{J K}^{-1}\text{mol}^{-1}$.
Barium hydroxide reacts readily with ammonium chloride when the substances are mixed at room temperature. $\text{Ba(OH)}_2\cdot 8\text{H}_2\text{O}(s) + 2\text{NH}_4\text{Cl}(s) \rightarrow 2\text{NH}_3(g) + \text{BaCl}_2\cdot 2\text{H}_2\text{O}(s) + 8\text{H}_2\text{O}(l)$, $\Delta H_r^\circ = +133\,\text{kJ mol}^{-1}$. Calculate the standard Gibbs free energy change, $\Delta G^\circ$, for this reaction at $25\,^\circ\text{C}$ using the standard entropy data given in Table 1.2.
Suggest how the lattice energy of $\text{BaSO}_4 (s)$ compares with the lattice energy of $\text{Cs}_2\text{SO}_4 (s)$. Explain your answer.