Non-isothermal decomposition of rhodium acetate monohydrate - a kinetic and thermodynamic study

The non-isothermal decomposition of rhodium acetate monohydrate (Rh(CH3COO) (2). H2O) was studied on heating to the formation of rhodium metal at 400 d egrees C in N-2 atmosphere using thermogravimetry (TGA), derivative thermog ravimetry (DTG), differential thermal analysis (DTA) and differential scann ing calorimetry (DSC). X-ray powder diffraction and IR spectroscopy were us ed for identification of the solid decomposition products. The variation of the rate of heating was used to calculate the activation energy (E-a) and the frequency factor (In A) for the dehydration and the decomposition proce sses. In addition, the enthalpy (Delta H), heat capacity (C-p) and the entr opy (Delta S) changes were also calculated from the DSC measurements. The f inal mass loss after complete decomposition was found to increase appreciab ly with increasing of the heating rate. The activation energy (E-a) togethe r with the enthalpy (Delta H) were found to be relatively small compared wi th those reported for some other reducible metal acetates. (C) 2000 Elsevie r Science B.V. All rights reserved.