[4] 6. Use Chen's equation to estimate the heat of vaporization of acetone at its normal boiling point. AR, = RT. (3.978 (7,/ 72) - 3.938 + 1.555 In p. 1.07 - (7./T.) (9.14) where T, is the normal boiling point of the liquid in kelvin, Te is the critical temperature in kelvin, and Pe is the critical pressure in atmospheres.