Then we have to take into account all the phase changes: dehydration, hydration, evaporation, condensation, desorption and adsorption.
For instance in dehydration we have the solid matrix, we give energy and free chemically adsorbed water.
The opposite is hydration, where we have the chemically adsorbed energy, which gives rise to the solid matrix and free energy.
Then evaporation, where we have the capillary water. We give energy and obtain water vapour, while in condensation we have the water vapour which gives rise to capillary water and free energy.
Finally desorption, we have the physically adsorbed water, we give energy and obtain water vapour. The opposite is starting from water vapour in adsorption, we obtain physically adsorbed water and free energy.