What does the term lattice energy mean?
Write an equation to show the lattice energy of MgO.
The apparatus shown in the diagram can be used to measure the enthalpy change of formation of magnesium oxide, $\Delta H_f^\circ(\text{MgO})$. State the measurements you would need to take with this apparatus in order to calculate $\Delta H_f^\circ(\text{MgO})$.
Using the data below, together with suitable data from the Data Booklet, calculate a value of $\Delta H_f^\circ(\text{MgO})$. Lattice energy of $\text{MgO(s)} = -3791\ \text{kJ mol}^{-1}$ Enthalpy change of atomisation of Mg $= +148\ \text{kJ mol}^{-1}$ Electron affinity of the oxygen atom $= -141\ \text{kJ mol}^{-1}$ Electron affinity of the oxygen anion, $\text{O}^- = +798\ \text{kJ mol}^{-1}$
Write equations, including state symbols, for any reactions of the two oxides below with water. Then suggest pH values for the solutions formed. Oxides: $\text{Na}_2\text{O}$ and $\text{MgO}$.