EQUILIBRIUM IN SATURATED CA(OH)(2) SOLUTIONS - PARAMETERS AND DISSOCIATION-CONSTANTS

A new computer program has been developed for the calculation of pH, p OH, hydroxide ion concentration m(OH), species distribution coefficien ts alpha(i), ionic activity coefficients gamma(i) ionic strength l, bu ffer capacity beta, solubility product K-s0, and the two dissociation constants, K-b1 and K-b2, corresponding, respectively, to first and se cond dissociation steps of Ca(OH)(2) in aqueous solution. Previously d eveloped methodology, for the calculation of pH, alpha(i), gamma(i) I, and beta parameters of pH buffer solutions, starting from the corresp onding acidity constants, has been adapted for the case of aqueous Ca( OH)(2) solutions, for which the pertinent stoichiometric relationships are different from those applicable to mixtures of acids and their sa lts. The results show that, contrary to what is currently assumed, the first dissociation is far from complete. Values are given for the con centrations and activities of species Ca(OH)(2)(aq), Ca(OH)(+)(aq), an d Ca2+(aq) in saturated calcium hydroxide solutions at 25 degrees C.