SOLUBILITY OF GYPSUM IN AQUEOUS ELECTROLYTES AS AFFECTED BY ION ASSOCIATION AND IONIC STRENGTHS UP TO 0.15M AND ST 25 DEGREES C

A computer program is utilized to calculate ion association and solubility of gypsum in aqueous electrolyte systems (NaCl, MgCl2, CaCl2, Na2SO4, MgSO4, CaSO4, or their mixtures) oflimited ionic strength and at 25° C. The Fortran program accepts nonequilibrium input solute concentrations and considers simultaneously the Debye-Hückel theory, KSP of gypsum, and KD of CaSO4°, MgSO4°, and NaSO4° to predict equilibrium concentrations without prior measurement in the equilibrium state. Predicted cationic activities and stoichiometric solubility of gypsum are in general agreement with observed values in this and other studies. This computer approach provides a comprehensive description of various solution parameters heretofore not fully realized for the above systems. © 1969, American Chemical Society. All rights reserved.