METHOD OF DETERMINING SOLUBILITY AND IONIC PRODUCTS FOR LOW-SOLUBLE AND COMPLEX COMPOUNDS

摘要

FIELD: thermodynamic analysis.;SUBSTANCE: invention relates to methods for determining thermodynamic, real, and conventional equilibrium constants of inorganic and organic substances employed in theoretical and applied chemistry fields. Method of determining conventional solubility products and ionic products comprises potentiometric titration wherein, in the course of individual potentiometric titration, limiting degree of proceeding of analytical reaction is achieved through synchronously decreasing concentrations of components to their limiting state and, when the titration potential jump disappears, one calculates molar concentration of component forming low-soluble compound in stoichiometry point and finds equilibrium concentration of the subject substance using following relationships: M_sp = (100-C_lim)·M_det·V_det/(V_det+V_titr)·100% and S_MnAm = (100-C_lim)·M_det·M_titr/(n·M_det + m·M_titr)·100%, where C_lim denotes limiting degree of proceeding of an individual analytical reaction, mole/L; S_MnAm solubility of low-soluble substance, mole/L; M_det initial molar concentration of component to be determined, mole/L; V_titr volume of titrant, ml; M_titr molar concentration of titrant, mole/L; n and m are stoichiometric coefficients. From M_sp and S_MnAm, conventional solubility product and ionic product, respectively, are found taking into account m and n values for given salt.;EFFECT: simplified determination procedure and enabled estimation of determination error.;5 tbl