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Australian Journal of Chemistry Australian Journal of Chemistry Society
An international journal for chemical science
RESEARCH ARTICLE

The decomposition of permanganate in molten alkali-metal nitrates

RB Temple and GW Thickett

Australian Journal of Chemistry 27(5) 943 - 953
Published: 1974

Abstract

The decomposition of MnO4- has been studied in molten (K/Li)NO3 eutectic at temperatures between 150º and 200ºC. The rate of decomposition in a Pyrex vessel increased in the presence of traces of NO2-, Br- and CN- and of the manganate(1V) precipitate produced in the decomposition. Various transition and heavy metal ions were also found to accelerate the decomposition of MnO4- : the rate law appears to be -d[MnO4-]/dt = k[Mn+]2/n[MnO4-] where n = oxidation state of metal ion M which was added to the melt solution of MnO4- (in the presence of a fixed weight of insoluble reaction product). Nickel and cobalt(11) ions are oxidized by MnO4- to insoluble nickel(111) and cobalt(111) manganates(1V). Whilst NO2- produced by the thermal decomposition of NO3- appears to be the active reductant in (K/Li)NO3 melts, the reaction is complicated by being partly heterogeneous. The method of preparation of the reaction product critically affects the rate constant k.

https://doi.org/10.1071/CH9740943

© CSIRO 1974

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