Describe and explain the way the solubility of the Group 2 sulfates changes down the group.
The decomposition temperatures of Group 2 peroxides, $\text{MO}_2$, follow the same pattern as those of Group 2 carbonates. State which of barium peroxide, $\text{BaO}_2$, and calcium peroxide, $\text{CaO}_2$, decomposes at the lower temperature. Explain your answer.
Magnesium iodate(V), $\text{Mg(IO}_3)_2$, breaks down on heating to form magnesium oxide, oxygen and iodine. Write an equation for this reaction.
Calcium iodate(V), $\text{Ca(IO}_3)_2$, is only sparingly soluble in water. Write an expression for the solubility product, $K_{\text{sp}}$, of $\text{Ca(IO}_3)_2$, and state its units.
Calculate the numerical value for $K_{\text{sp}}$ of $\text{Ca(IO}_3)_2$ at $298\,\text{K}$.
When a few $\text{cm}^3$ of concentrated $\text{Ca(NO}_3)_2(aq)$ is added to a saturated solution of $\text{Ca(IO}_3)_2$, a white precipitate appears. Identify the white precipitate and explain this observation.
Iodised salt is sodium chloride mixed with a small amount of sodium iodate(V), $\text{NaIO}_3$. $50.00\,\text{g}$ of iodised salt is dissolved in distilled water and the solution is made up to $250\,\text{cm}^3$ in a volumetric flask with distilled water. $50.0\,\text{cm}^3$ of this solution is pipetted into an excess of aqueous acidified potassium iodide. $\text{IO}_3^- + 5\text{I}^- + 6\text{H}^+ \rightarrow 3\text{I}_2 + 3\text{H}_2\text{O}$. The iodine produced requires $12.40\,\text{cm}^3$ of $0.00200\,\text{mol dm}^{-3}$ aqueous sodium thiosulfate solution for complete reaction. $\text{I}_2 + 2\text{S}_2\text{O}_3^{2-} \rightarrow 2\text{I}^- + \text{S}_4\text{O}_6^{2-}$. Calculate the mass of sodium iodate(V) present in $50.00\,\text{g}$ of iodised salt.
The half-equation for the reduction of iodate(V) ions is shown. $\text{IO}_3^- + 6\text{H}^+ + 5\text{e}^- \rightarrow \tfrac{1}{2}\text{I}_2 + 3\text{H}_2\text{O}\quad E^\circ = +1.19\,\text{V}$. Use data from the Data Booklet to predict whether a reaction is feasible when aqueous solutions of acidified iodate(V) ions and bromide ions are mixed. Explain your answer.
Iodate(V) ions react with sulfite ions in acidic solution at $\text{pH} = 5.00$ as shown. $\text{IO}_3^- + 3\text{SO}_3^{2-} \rightarrow \text{I}^- + 3\text{SO}_4^{2-}$. The initial rate of reaction was found to be first order with respect to $\text{IO}_3^-$, first order with respect to $\text{SO}_3^{2-}$ and first order with respect to $\text{H}^+$. Write the rate equation for this reaction, stating the units of the rate constant, $k$.
The rate of reaction depends on the pH of the solution. Assume all other concentrations stay unchanged. Use the expression $x = \dfrac{\text{rate at pH }5.00}{\text{rate at pH }4.00}$ to calculate the value of $x$.