1. The problem statement, all variables and given/known data Find the standard enthalpy of vaporization, standard entropy of vaporization and standard free energy of vaporization. Given are two pairs of temperature and vapor pressure for Arsine, AsH3. Vapor pressure is 35 Torr at -111.95C and 253 Torr at -83.6C. T [K] = T [C] + 273.15 2. Relevant equations ln(P2/P1) = H*((1/T1) - (1/T2))/R H is the standard entropy of vaporization and R the gas constant. 3. The attempt at a solution To find the standard enthalpy I simply solved for H and substituted all the values. The pressures as they are, since the units cancel, and the temperature in kelvin. I got H to be about 17.7 kJ/mol but is supposed to be 28.3 kJ/mol according to solutions.