A solution is prepared by mixing 0.0200 mol CH2Cl2 and 0.0500 mol CH2Br2 at 25°C. Assuming the solution is ideal, calculate the composition of the vapor (in terms of mole fractions) at 25°C. At 25°C, the vapor pressures of pure CH2Cl2 and pure CH2Br2 are 133 and 11.4 torr, respectively.

Answer 1

Convert moles CH2Cl2 to mole fraction.
moles fraction CH2Cl2 = moles CH2Cl2/total moles.
Convert CH3Br2 to mole fraction the same way.
Then calculate the partial pressure of each gas.
P_CH2Cl2 = X_CH2Cl2*P^{o_{(pure solvent)}.
Do the same for CH2Br2, then add the partial pressures to obtain the total pressure.}