Original scientific paper

Stability Constants of Chlorocadmium Complexes in t-Butanol + Water Mixtures (w_t-BuOH = 10%, 30%, and 50%) from Electromotive Force Measurements

Marija Višić ; Faculty of Natural Sciences and Arts, University of Split, Teslina 12, HR-21000 Split, Croatia
Renato Tomaš ; Department of Physical Chemistry, Faculty of Chemical Technology, University of Split, Teslina 10, HR-21000 Split, Croatia
Ivica Mekjavić ; Department of Physical Chemistry, Faculty of Chemical Technology, University of Split, Teslina 10, HR-21000 Split, Croatia

Abstract

Potentiometric method was applied in determining the stability constants (K'_n) of cadmium chloride complexes at different ionic strengths in t-butanol + water mixtures (w_t-BuOH = 10%, 30%, and 50%) at 288.15, 298.15 and 313.15 K, respectively. Calculation of the constants was performed by graphical Leden’s method and by numerical methods: orthogonal polynomials, and nonlinear regression without and with scaling (weighting). The values obtained by the method of orthogonal polynomials were used to establish thermodynamic stability constants (K°_n) of CdCl+, CdCl₂ and CdCl₃- complexes in 10 mass per cent t-butanol and 30 mass per cent at 288.15 and 298.15 K, and also at 313.15 K and in 50 mass per cent for CdClJ complex. Based on temperature dependence for K°_n, the thermodynamic quantities were calculated for reactions forming complexes, which are endothermic and result in increased entropy. Dependences for K°_n and for thermodynamic quantities ΔH° and ΔS° on the solvent dielectric constant are presented and were compared with analogous literature data in 2-propanol + water and acetone + water mixtures.

Keywords

Hrčak ID:

132133

URI

https://hrcak.srce.hr/132133

Publication date:

1.3.1999.

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