Calcium nitride, Ca3N2, reacts readily with water to form a white precipitate suspended in an alkaline solution. The oxidation number of nitrogen does not change during the reaction. Construct an equation for the reaction of Ca3N2 with water.

1. (a)Calcium nitride, Ca3N2, reacts readily with water to form a white precipitate suspended in an alkaline solution. The oxidation number of nitrogen does not change during the reaction. Construct an equation for the reaction of Ca3N2 with water.[2]
2. (b)The enthalpy changes of solution, ΔH°sol, of the hydroxides of the Group 2 elements become less endothermic down the group. State and explain the trend in the solubilities of the Group 2 hydroxides.[3]
3. (c)Complete the energy cycle to show the enthalpy changes that occur in the transformations between aqueous ions, gaseous ions and an ionic solid. On your diagram label each enthalpy change with its appropriate symbol; lattice energy, ΔH°latt, enthalpy change of hydration, ∆H°hyd, or enthalpy change of solution, ΔH°sol. Complete the three arrows showing the correct direction of each enthalpy change. aqueous ions ionic solid gaseous ions[3]
4. (d)The numerical value of the solubility product, Ksp, of CaF2 is 3.45 × 10–11 at 298 K.
5. (d)(i)Write an expression for the solubility product of CaF2. Include its units. Ksp =[2]
6. (d)(ii)Calculate the solubility of CaF2 at 298 K. solubility =[1]