Question #b39e8

1 Answer
Jul 20, 2017

By Clausius - Clapeyron equation weknow

color(red)(ln(P_1/P_2) = (DeltaH_"vap")/R xx (1/T_2 - 1/T_1)

Where

P_1 is the vapor pressure of the liquid at T_1K

P_2 is the vapor pressure of the liquid at T_2K

R is the universal gas constant, equal to "8.314J mol"^(-1)"K"^(-1)

DeltaH_"vap"= "enthalpy of vaporization of the liquid"

Given

T_1=273+5=278K

P_1=8.54mm of Hg

T_2=273+120=393K

DeltaH_"vap"=41.8kJmol^-1"=41.8xx10^3Jmol^-1

P_2=?

Inserting these in above equation

color(blue)(ln(P_1/P_2) = (DeltaH_"vap")/R xx (1/T_2 - 1/T_1)

=>color(blue)(ln(8.54/P_2) = (41.8xx10^3)/8.314xx (1/393 - 1/278)

=>color(blue)(ln(8.54)-lnP_2 = (41.8xx10^3)/8.314xx (1/393 - 1/278))

=>color(blue)(lnP_2 =ln(8.54)- (41.8xx10^3)/8.314xx (1/393 - 1/278))

=>color(blue)(lnP_2=7.437)

=>color(blue)(P_2=e^7.437~~1698mm)