Question If the enthalpy change of NH3 + H2O --> NH4OH is -80.8 KJ/mol does that mean if I add heat +80.8 KJ/mol to NH4OH I wuld get NH3 + H20 I am trying to find out how much energy I need to separate a given amount of ammonium hydroxide.
Answer Hi Emmanuel,
The answer is yes but it is not that simple. Amonium hydroxide is always giving off NH3, like all things it has a vapour pressure. The heat needed to do this is taken from the surroundings.
And when you have evolved a mole of NH3 it will have absorbed 80.8 KJ from the surroundings. As with all vapour pressures if you raise the temperature it will evolve NH3 faster.