Solid state reactions in the system oxalate-bromate-chromium(III) oxide

Abstract

The TG and DTA techniques in static air atmosphere have been employed to study the thermal behaviour of intimate mixtures comprising different mole ratios of potassium oxalate, potassium bromate and chromium(III) oxide. The products are characterised by chemical analysis, infrared spectroscopy and X-ray diffraction studies. The studies indicate that the onset of the reaction occurs after the dehydration of potassium oxalate around 200°C. Also it suggests that the chromium(III) oxide initiates the decomposition of potassium bromate at a lower temperature resulting in the liberation of oxygen which is utilised in the oxidative decomposition of potassium oxalate. With the stoichiometric amounts (3:3:1 molar ratio) of potassium bromate, potassium oxalate and chromium(III) oxide the reaction gives rise to a mixture of potassium chromate, potassium carbonate and potassium bromide in the molar ratio of 2:2:1.