Potentiometric study of Tungsten(VI) Complex Formation with Tartarate
| Authors | |
|---|---|
| Year of publication | 2000 |
| Type | Article in Periodical |
| Magazine / Source | Chem. Papers |
| MU Faculty or unit | |
| Citation | |
| Field | Analytic chemistry |
| Keywords | Complex equilibria; chemical model determination; tungstate; tartaric acid |
| Description | Complexation of tungstate with tartarate has been investigated by potentiometry in the pH range 2,5-7,5 in 1 M KNO3. The experimental data were evaluated with ESAB (for the calculation of protonation constants of tartarate) and OPIUM (for the formation constants of complexes) computer programs. A high number of chemical models including polynuclear complexes were considered and tested on a computer. The final model comprises five complexes that have a tungsten(VI):tartarate ratio 2:2 and 1:2. The following formation constants (Beta_pqr)were calculated: log Beta(212) = 16.6 +/- 0.1, log Beta(312) = 20.4 +/- 0.2, log Beta(412) = 23.9 +/- 0.1, log Beta(322) = 26.68 +/- 0.08, and log Beta(422) = 30.7 +/- 0.1, where p, q, r refer to stoichiometric coefficients in general formula (H)p(WO4)q(C4H4O6)r p-2q-2r. Structures of the complexes were proposed. |
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