Solved: For the reversible vaporization of water at $$100^0C$$ and 1 atmospheric pressure, $$Delta [Physics] y= 8525.8x+23.536 1. From the slope of the trendline, Chegg.com Standard enthalpy of vaporization (vapH) for water at 100C is 40.66 kJ.. Solved Heat, q, is energy transferred between a system and Chegg.com Predicting the Enthalpy of Vaporization and Calculating the Entropy of Vaporization of 87 Octane Gasoline Using Vapor Pressure Calculate the `K_b` for water given latent heat of vaporisation of water `540 Cal gm`.