Prediction of Heat of Solution and Heat of Combustion by Correlation Gas Chromatographic Method

Abstract

The enthalpy of solution (Δ H_sol) is an important thermodynamic property of a substance. It encompassesthe interaction between a substance with the stationary phase of a gas chromatographic (GC)column, which can be easily determined by equation (1)

lnk = ΔS_0(sol) -lnβ + z S_sol - ΔH_0(sol)/T - zδH_sol/T   (1)

where k is the retention factor, Δ S_0(sol) and Δ H_0(sol) are the entropy and enthalpy of solution, respectively, ofthe hypothetical compound with zero carbon atom, δS_sol and δH_sol are the increment in entropy and enthalpyper one carbon atom, respectively. T is the absolute temperature and β is the column phase ratio. zis the number of carbon atom of the homolog. Δ H_sol can be easily estimated from the sum of the twoenthalpic terms in eq.(1). In this study, heat of combustion (HG) of a substance was linearly correlated withΔ H_sol. The estimated values of HG for fatty acid methyl esters, n-paraffins and n-alcohols were comparedwith those reported in the literatures. The estimated HG values are very close to those reported in theliteratures.

Keywords : Fatty Acid Methyl Ester / Gas Chromatography / Heat of Solution / Heat of Combustion /n-Paraffins / n-Alcohols