Determination of stability constants of the NiCO30, ZnCO30, and CdCO30 complexes using solubilities of corresponding metal carbonates in aqueous solutions

Abstract

The solubilities of NiCO₃, ZnCO₃, and CdCO₃ in NaClO₄–NaHCO₃–Na₂CO₃ solutions are studied experimentally at 25°C and ionic strength of 0.1. The resulting data are used to determine the concentration stability constants of NiCO₃⁰, ZnCO₃⁰, and CdCO₃⁰ complexes in aqueous solutions (they are equal to 810, 12700, and 17900, respectively; log \(K'_{MCO_3^0 } \) = 2.90 ± 0.14, 4.10 ± 0.20, and 4.25 ± 0.04) and to calculate their thermodynamic values (6.45 × 10³, 1.01 × 10⁵, and 1.43 × 10⁵, respectively). The logarithms of stability constants of carbonate complexes are found to be inversely dependent on the solubility products of their metal carbonates.