MECHANISM OF ION-EXCHANGE IN CRYSTALLINE ZIRCONIUM-PHOSPHATES .10. CALORIMETRIC DETERMINATION OF HEATS OF NA+-H+ EXCHANGE 1A
Academic Article
Overview
Identity
Additional Document Info
Other
View All
Overview
abstract
The heats of Na+-H+ exchange on three samples of zirconium phosphate of widely different crystallinities have been determined calorimetrically. For the crystalline sample the first 50% of exchange is exothermic with H = -6.90 0.10 kcal/mol. The second half of the reaction is endothermic with H = +6.45 0.15 kcal/mol. The corresponding entropies accompanying these reactions are -31.0 0.1 and 0.0 0.1 eu. In the case of a gelatinous, nearly amorphous, exchanger the reaction is initially exothermic but then the heat function passes through a broad maximum and becomes progressively more endothermic. The overall reaction is endothermic with H = 2.0 0.2 kcal/mol and S = -14.8 1.3 eu. The semicrystalline exchanger exhibited heat effects surprisingly similar to those of the fully crystalline exchanger. Qualitative explanations for the observed results are presented.
