Low-temperature heat capacities and standard molar enthalpy of formation of pyridine-2,6-dicarboxylic acid

This paper reports that the low-temperature heat capacities of pyridine-2,6-dicarboxylic acid were measured by a precision automatic calorimeter over a temperature range from 78 K to 380 K.A polynomial equation of heat capacities as a function of temperature was fitted by the least-squares method.Based on the fitted polynomial,the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at intervals of 5 K.The constant-volume energy of combustion of the compound was determined by means of a precision rotating-bomb combustion calorimeter.The standard molar enthalpy of combustion of the compound was derived from the constant-volume energy of combustion.The standard molar enthalpy of formation of the compound was calculated from a combination of the datum of the standard molar enthalpy of combustion of the compound with other auxiliary thermodynamic quantities through a Hess thermochemical cycle.