ENTROPY OF ZEOLITIC WATER
Zeolite-water heat-pump system is suitable for effective use of low temperature heat sources such as solar energy and waste heats from factories, that is, for energy saving. The heat exchange function of zeolite owes obviously to the nature of the zeolitic water, the state of which can be described in terms of the entropy value as an independent component of H2O. Most entropy values of zeolitic water have been given so far to be intermediate between those of liquid water (69.9 J mol–1 K–1 at 298 K) and ice (41.5 J mol–1 K–1 at 273 K). The present calorimetric measurements proved, however, that the entropy value for Mg-exchanged A-type zeolite is so small, even at the ambient temperature, as to be compared with the residual entropy of ice at 0 K.