Thermal behaviour of chromium (III) perchlorate hexahydrate

Infrared absorption study of metal oxides in the low frequency region (700-240 cm−1)

Abstract: The characteristic frequencies of oxides of 52 metals have been studied in the region 700-240 cm−1. Data for oxides of metals of different valence states and the frequencies of polymorphic forms of several oxides are presented. A particle size of 10 μ or smaller was found to give the best representative spectrum.

Thermal decomposition of potassium perchlorate in presence of chromium(III) oxide and nickel(II) chromite(III)

Abstract: A study of the thermal decomposition of intimate mixtures of different molar ratios of potassium perchlorate and chromium(III) oxide, and potassium perchlorate and nickel(II) chromite(III) was conducted employing thermogravimetry, differential thermal analysis, chemical analysis, infrared spectroscopy and X-ray diffraction analysis. Upon heating to 400°C Cr(III), in 2:1 molar ratios, is oxidized to potassium dichromate. Only a stoichiometric amount of Cr(III) was oxidized from molar ratios less than 2:1, leaving behind excess Cr2O3 and NiCr2O4 whereas from molar ratios greater than 2:1, Cr(III) was completely oxidized and the excess KClO4 started decomposing around 410°C which is much below the decomposition temperature of pure KClO4.

On the reaction between molten lithium perchlorate and chromium(III) oxide

Abstract: The reaction at 300°C between molten lithium perchlorate and chromium(III) oxide gave lithium dichromate. When lithium perchlorate and chromium(III) oxide were in the formula weight ratio of 2:1 respectively, the chromium was oxidized completely into the hexavalent oxidation state, and only a negligible chloride percentage of 0·1 remained in the resulting lithium dichromate. Different formula weight ratios were taken for the reaction at 300°C. In the runs where the formula weight ratios of the perchlorate and oxide were lower than 2:1, the amount of chromium oxidized was higher than expected by the proposed route, and an explanation is given. Reactions with 51Cr2O3 showed that a very small amount of chromium volatilized. Results obtained from experiments both in vacuum and air were in very good agreement. A reaction mechanism is proposed.

Thermal decomposition of thallium(I) perchlorate in presence of chromium(III) oxide

Abstract: Thermal decomposition of an intimate mixture of thallium(I) perchlorate and chromium(III) oxide revealed that chromium(III) oxide lowers the decomposition temperature of thallium(I) perchlorate and is oxidized into hexavalent state to give thallium(I) dichromate. The thermal decomposition was followed by constant temperature heating, thermogravimetry and differential thermal analysis. The reaction products were characterized by chemical analysis, X-ray diffraction and infrared spectral measurements.