Kinetics of the base decomposition of dodecatungstophosphate(3–) in weakly alkaline solutions
- 1 January 1983
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 12,p. 2609-2612
- https://doi.org/10.1039/dt9830002609
Abstract
The kinetics of the decomposition of [PW12O40]3–(1.5 × 10–5 mol dm–3) to [WO4]2– and [PO4]3– has been studied in the range pH 7–9 at an ionic strength of 0.1 mol dm–3. The reaction proceeds via the intermediates [PW11O39]7– and [PW9O34]9–. Only the final stage, the hydrolysis of [PW9O34]9–, was studied in detail. The [PW9O34]9– ion exists in rapid equilibrium with [HPW9O34]8– and [H2PW9O34]7– with the unprotonated and monoprotonated ions decomposing via first-order kinetics. The pKa values for [H2PW9O34]7– and [HPW9O34]8– were determined as 7.3 and 9.2 respectively, and the rate constants for decomposition of [HPW9O34]8– and [PW9O34]9– as 8.0 × 10–4 and 6.3 × 10–3 s–1 respectively at 25.6 °C.Keywords
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