Question

1) The enthalpy of vaporization for a liquid is found to be 14.4 kJ mol- at 180 K, its normal boiling point. The molar volumes of the liquid and the vapour at the boiling point are are 115 mL mol-1, and 14.5 L mol-1, respectively. a) Use the Clapeyron equation to estimage the temperature dependence of the vapour pressure (dp/dT) at the normal boiling point. b) Use the Clausius-Clapeyron equation to estimate dp/dT. c) Does the Clausius-Clapeyron equation overestimate or underestimate the temperature dependence of the vapour pressure? What is the percent error of this estimation?

Answer 1

Acc. to clapeyron equation = 14.4 x 103 J moit (180k ) (14.5 x103 - 105X10-4) mmo- Im3 = 1000 L. - 5.56 kPa kn dP AH хр as dimp = dp de RT2 - 14.4x10 3 I mot x 1.013 x 105 Pa 8.314 J K -1 moll (180 k 32 = 5.48 x Pa k-1 Percentage euror - 5.56 -5.42 x 100 = 2.5% 5:56 to Clausis - clapeyson has approximatel Vivar Vaginn uap,