THERMAL-DECOMPOSITION OF FORMATES OF CERTAIN D-ELEMENTS AND F-ELEMENTS

A thermogravimetric study has been made of the character of thermal conversions, in air, of the formates of chromium(III), manganese(II), iron(III), cobalt(II), nickel(II), copper(II), lanthanum(III), cerium(III), and praseodymium(III). The intermediate products in the decomposition of the formates of iron(III), cobalt(II), and nickel(II) are the oxides MeO2, and the final products are the oxides Cr2O3, Co3O4, and NiO. In the thermal decomposition of lanthanum formate in the 360-400-degrees-C interval, the oxocarbonate is formed; at higher temperatures, the oxocarbonate decomposes slowly to the oxide. The process of dehydration of the formates influences their thermal stability, as a consequence of local hydrolysis of the metal cation. A correlation has been established between the temperature corresponding to the maximum decomposition rate for d-element formates and the heat of decomposition.