Heat capacities of α,ω-dichloroalkanes at temperatures from 284.15 K to 353.15 K and a group additivity analysis

Heat capacities at constant pressure of five alpha,omega-dichloroalkanes (1,2-dichloroethane, 1,3-dichloropropane, 1,4-dichlorobutane, 1,5-dichloropentane, 1,6-dichlorohexane) were measured at temperatures ranging from 284 K to 353 K by using a highly sensitive Tian-Calvet differential scanning microcalorimeter (DSC). Changes in the standard procedures increased the accuracy of C-p measurements. The influence of the evaporation heat effect on the C-p value is analyzed. In the described method, the uncertainty of the measurements is estimated to be +/-0.15% for uncertainties arising solely from the measurement system and method. The group contributions to C-p for CH2 and Cl and their temperature dependence were determined by a group additivity analysis.