The lattice energy* of Nal is \(-686 \mathrm{kJ} / \mathrm{mol}\) , and the enthalpy of hydration is \(-694 \mathrm{kJ} / \mathrm{mol}\) . Calculate the enthalpy of solution per mole of solid Nal. Describe the process to which this enthalpy change applies.

: Lattice energy (LE) of NaI = -686 kJ/mol Enthalpy of hydration (HH) of NaI = -694 kJ/mol

: Enthalpy of Solution (ES) = Lattice energy (LE) + Enthalpy of hydration (HH)

: ES = (-686 kJ/mol) + (-694 kJ/mol)

: ES = -686 - 694 ES = -1380 kJ/mol

: The calculated enthalpy change (-1380 kJ/mol) corresponds to the enthalpy of solution for solid NaI. This process involves the dissolution of one mole of solid NaI in a large amount of water. The enthalpy of solution is the sum of the energy required to break the ionic lattice in the solid (lattice energy) and the energy released when new interactions are formed between the ions and water molecules (enthalpy of hydration). In this case, the overall enthalpy change is negative, indicating that the dissolution process is exothermic and releases energy. The formation of new ion-water interactions is more energetically favorable than maintaining the ionic lattice in the solid state, and thus NaI dissolves readily in water.