The heat of hydration is the enthalpy change associated with the process of dissolving a substance in water to form a hydrated compound. In this case, we are given the enthalpy change of the reaction between anhydrous magnesium sulfate MgSO4 and water to produce hydrated magnesium sulfate MgSO47H2O .The reaction can be represented as follows:MgSO4 s + 7H2O l MgSO47H2O s We are given that the enthalpy change H for this reaction is -108 kJ/mol. Since the reaction involves 1 mol of anhydrous magnesium sulfate and 1 mol of hydrated magnesium sulfate, the heat of hydration for this reaction is simply the enthalpy change of the reaction.Therefore, the heat of hydration for the reaction between 1 mol of anhydrous magnesium sulfate and enough water to produce 1 mol of hydrated magnesium sulfate is -108 kJ/mol.