The information on the sublimation and vaporisation of ammonia given below will enable the triple point and three latent heats at the triple point to be determined. The sum of the latent heat of melting plus the latent heat of vaporisation is equal to the latent heat of sublimation at the triple point. The solid can be changed directly from solid to vapour with latent heat . It can also be changed from solid to liquid and from liquid to vapour and the latent heat required must be the same. Hence
Lₛ = Lᵥ + Lₘ
The vapour pressure in millimetres of H of solid ammonia and for liquid ammonia respectively are given byP=23.03-3754T (o) ,P=19.49-3063T ()