Clapeyron Equation Quiz: Calculating Vapor Pressure and Percentage Error, Quizzes of Physical Chemistry

Download Clapeyron Equation Quiz: Calculating Vapor Pressure and Percentage Error and more Quizzes Physical Chemistry in PDF only on Docsity! Chem-433 Quiz #9: 10/28/98 Name: Key Possibly useful information: dp dT =
trsH T
trsV p = peVm
P=RT d ln p dT =
vapH RT 2 p = p exp 
vapH R  1 T 1 T   p = p +
fusH
fusV ln T T  R = 8:3145 J
mol1
K1 R = 0:08206 L
atm
mol1
K1 1.(10 points) The enthalpy of vaporization of a certain liquid is found to be 14.4 kJ mol1 at 180K, its normal boiling point. The molar volumes of the liquid and its vapor at the boiling point are 0.115 L mol1 and 14.5 L mol1, respectively. (a) Calculate dp=dT (in units of atm K1) from the Clapeyron equation. dp dT =
vapH T
vapV = 14; 400J=mol (180K)(14:5L
mol1 0:115L
mol1  0:08206(L
atm)=(mol
K) 8:3145J=(mol
K) dp dT = 0:0549atm
K1 (b) Calculate the percentage error in dp=dT if it is calculated from the Clausius-Clapeyron equation instead of the Clapeyron equation. d ln p dT =
vapH RT 2 dp dT = p
vapH RT 2 = (1atm)(14; 400J=mol (8:3145J=(mol
K)(180K)2 = 0:0535atm
K1 The percent error is given by Error = 0:0549 0:0535 0:0549  100 = 2:55%