Solubility product and total solubility in water of copper(II) nicotinate

•A method has been developed for determining the solubility product of Cu(II) salts by potentiometric titration with Cu indicator electrode.•Solubility product and total solubility of copper (II) nicotinate have been determined.•Cumulative stability constant of copper (II) nicotinate complex in aqueous solution has been estimated. A method for determining the solubility product of sparingly soluble copper (II) salts based on the data of precipitation potentiometric titration with a copper indicator electrode is proposed and substantiated. For the first time, a systematic study of the solubility in aqueous media of copper (II) nicotinate (pyridine-3-carboxylate, CuNic2) has been carried out. The solubility product KSP(CuNic2) was determined from the precipitation titration curves of Cu(NO3)2 solution with sodium nicotinate. The value of log10KSP(CuNic2) = –14.10 ± 0.31 was obtained, and it does not depend on temperature in the range of 14–45 °C. The total solubility of CuNic2 was estimated by atomic absorption spectroscopy; in aqueous solutions with pH 6.3–6.5 containing ∼ 0.07 mol kg−1 NaNic and ∼ 0.04 mol kg−1 NaNO3, it is equal to (1.63 ± 0.12) × 10–5 mol kg−1 at a temperature of 20–25 °C. The cumulative stability constant of the CuNic2(aq) complex was estimated from the values of the solubility product and total solubility: log10β2 = 9.31 ± 0.31 (20–25 °C).