Question #b39e8

1 Answer
P dilip_k
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)#

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