Why NaOH reaction with water is exothermic ?

The following reaction is under consideration

NaOH(s) + H2O(l) => Na+ + OH- + H20 +HEAT

I predict that when NaOH(s) is added into H2O(l) heat will be formed as NaOH dissociates into sodium cations and hydroxide anions. I assume this as NaOH is completely ionic, containing sodium ions and hydroxide ions and water is polar substance. If this is true, the enthalpy of solution for NaOH(s) must be negative i.e. the dissolution is exothermic. Inin chemistry we have an empirical rule: polar substances are soluble in polar solvents and non-polar substances in non-polar solvents.


Thank You
Ruchi
Askiitians Faculty