Industrial & Engineering Chemistry Research, Vol.49, No.12, 5543-5548, 2010
Heat Capacity, Enthalpy of Formation, and Entropy of Methyl Carbamate
The heat capacity (C-p) of methyl carbamate (MC) was measured with an adiabatic calorimeter. The standard enthalpy of formation (Delta H-f(0)(cr, 298.15 K)) and the standard entropy (S-0(cr, 298.15 K)) for MC were determined. Thus, C-p(T) values of MC were obtained for the crystal and liquid forms in the temperature range of 298.15-433.10 K. A quadratic trinomial was used to correlate the data of C-p(T). The enthalpy of fusion of MC was measured using differential scanning calorimetry (DSC), and its sublimation enthalpy was estimated. The gas-phase standard enthalpy of formation (Delta H-f(0) (g, 298.15 K)) of MC was calculated via the method of group contribution developed by Benson. Based on the above data, the values of Delta H-f(0) (cr, 298.15 K) and S-0 (cr, 298.15 K) of MC were estimated to be -513.57 kJ/mol and 77.1 J mol(-1) K-1, respectively. A thermochemical cycle including a reversible reaction was designed to examine the reliability of the estimated values by measuring the equilibrium constant of the reaction. The results showed that the estimated values for MC were acceptable.