Potassium chloride, KCl, and magnesium chloride, MgCl₂, are both ionic solids. Table 1.1 energy change value/kJ mol⁻¹ standard enthalpy change of solution, ΔH°sol, of KCI +15 lattice energy, ΔH°latt, of KCl(s) -701 standard enthalpy change of hydration, ΔH°hyd, of K⁺ -322 standard enthalpy change of hydration, ΔH°hyd, of Cl⁻ -364 standard enthalpy change of solution, ΔH°sol, of MgCl₂ -155 lattice energy, ΔH°latt, of MgCl₂(s) -2493