Heat capacities and derived thermodynamic functions of n-nonadecane and n-eicosane between 10 K and 390 K

Heat capacity measurements were made on n-nonadecane and n-eicosane from 10 K to 390 K with an adiabatic calorimeter. These measurements were used to calculate the entropy and the enthalpy relative to 0 K. The sum of the enth alpy of the solid-solid transition and of melting of n-nonadecane is 62659 +/- 20 J . mol(-1) at the triple point, 305.00 K. The enthalpy of melting o f n-eicosane was calculated to be 69922 +/- 100 J . mol(-1) at the triple p oint, 309.65 K. The entropies were extrapolated from the liquid phase just above the melting point to 298.15 K and found to be respectively 715.8 and 748.1 J K-1 . mol(-1). The crystallization behavior of both compounds is di scussed.