The speciation of (CH3)2Sn2+ in electrolyte solution containing the major components of natural waters

Abstract

Hydrolysis constants of dimethyltin(IV) cation, in different salt solutions (CaCl2: 0.15 ≤ I ≤ 0.90; MgCl2: 0.30 ≤ I ≤ 0.60; NaCl-–NaClO4, NaCl-–NaNO3 mixtures: I = 3; NaCl-–Na2SO4 mixtures: I = 1 mol dm-3) were determined by potentiometric ([H+]-glass electrode) measurements. These data, together with previous data (De Stefano et al., 1996b) were interpreted in terms of DHT (Debye–Huckel type) and Pitzer equations. The mixed electrolyte solution results also allowed us to obtain Θ and Ψ parameters for the Pitzer equation. Calorimetric measurements were made at different ionic strengths in order to find the temperature dependence of hydrolysis constants and of the relative interaction parameters. The body of results allows us to determine the speciation of natural waters in a wide range of ionic strengths and temperatures.