Question

At 63.5 °C, the vapor pressure of H 2 O is 175 torr, and that of ethanol (C 2 H 5 OH) is 400 torr. A

solution is made by mixing equal masses of H 2 O and C 2 H 5 OH, 1 g each. (a) What is the mole

fraction of ethanol in the solution? (b) Assuming ideal-solution behavior, what is the vapor

pressure of the solution at 63.5 °C?

Answer 1

a) XC2H5OH = $\frac{0.0217}{0.0217+0.05549}$

XC2H5OH = 0.28

b) Finding vapor pressure Pt= P_H2O +P_C2H5OH

_{= 126 Torr + 112 Torr}

_{= 238 Torr}