Chapter 12, Problem 123RQ

When a 10.0 molar solution of sodium hydroxide in water is prepared, the beaker becomes very hot. Once the solution cools to room temperature, it is diluted with an equal volume of water and again the solution becomes very warm. Noting that a reaction that is exothermic in one direction must be endothermic in the opposite direction, provide an explanation that makes sense of the observations above.