A person working in a company that manufactures absorption refrigerator told me that when Ammonia dissolves in water, the water temperature rises. In short, Ammonia absorption is water is exothermic. If it's true, then what's the reason behind it? Is it due to the fact that the latent heat of vaporisation of the Ammonia is added to the gross enthalpy of the mixture and that's why the temperature rises? If that's true then it's true for other gas/vapour too. Those who have good knowledge about this matter kindly explain.