Molar heat capacities of Chemical Solvents used for the Absorption of Carbon Dioxide

Abstract

The molar heat capacity, Cp, is a key thermo physical quantity needed for thermodynamic calculations. It is crucial for designing chemical processes as well as for the progress of thermodynamic theories. Knowledge of the heat capacities of liquids as a function of temperature renders some insight into their molecular structure and provides information on intermolecular interactions.Thermochemical and thermodynamic calculations depend heavily on the temperature dependencies of the constant pressure heat capacities of liquid phases. This work reports measured molar heat capacities of 44 pure solvents in the temperature range 303.15 to 393.15 K at atmospheric pressure. The structural similarities in this set of compounds led us to explore the application of group additivity analysis to the reported heat capacity data. Two analyses are reported: the first yields estimates of CH3, CH2, CH, NH2, NH, N and OH group contributions to the molar heat capacities at each investigated temperature; the second analysis utilizes a molecular connectivity approach to obtain a single equation that models the molar heat capacities of the amines over the investigated temperature range. Absolute average deviations for the group additivity analysis was found to be less than 3% and for the molecular connectivity analysis was found to be less than 6%.