2. Relevant equations d ln(Psat) / d (1/T) = -ΔHvap/R (Clausius-Clapeyron) 3. The attempt at a solution When solving for the enthalpy of vaporization using the Clausius-Clapeyron equation, is the resulting value an average over the temperature range? I assume this is the case, because enthalpy of vaporization is dependent on temperature. I found the enthalpy of vaporization for carbon dioxide from 220K to 300K to be 16.59 kJ/mol (using the Clausius-Clapeyron equation) and tabulated saturation pressures. I'm comparing this to the value I get from Hv-Hl=ΔHvap. When I take an average (arithmetic mean) of these values over the same temperature range, I get a value of 11.4 kJ/mol. Why is there such a difference between using these two methods?