Complete the energy cycle for the enthalpy change of solution and the lattice energy of potassium chloride, $\text{KCl}$, together with the relevant enthalpy changes of hydration. Add a label to your diagram. State symbols must be shown.
Using the information in Table 1.1, calculate the enthalpy change of hydration of magnesium ions, $\text{Mg}^{2+}$. Show your working.
Explain why the lattice energy of $\text{MgCl}_2$ is more exothermic than the lattice energy of $\text{KCl}$.
Define the term enthalpy change of atomisation.
Define the term first electron affinity.
Explain what is meant by entropy, $S$.
Potassium chloride is very soluble in water at $20\,^{\circ}\text{C}$. Explain the solubility of potassium chloride with reference to change in entropy, $\Delta S$.
Use the Gibbs equation and your answer to part (e)(ii) to predict whether potassium chloride is more soluble in water at $20\,^{\circ}\text{C}$ or at $80\,^{\circ}\text{C}$. Explain your answer.