Final answer:
To find the mass fractions of benzene in the liquid and vapour phases of a mixture, one must use the Antoine equation to obtain the pure component vapour pressures and apply Raoult's Law and Dalton's Law to determine the mole fractions, which can be converted to mass fractions.
Step-by-step explanation:
The question is about determining the mass fractions of benzene (C6H6) and o-xylene (C8H10) in both liquid and vapour phases in a mixture at 225°C and 1000 kPa(abs) pressure. To solve this question, we would use the Antoine equation which relates the vapour pressure of a pure component to temperature:
P = 10^(A - B / (T + C))
To determine the mass fraction of benzene in the liquid phase, we must assume that the liquid is an ideal solution obeying Raoult's Law, and for the gas phase, we assume an ideal gas mixture. We would need to calculate the vapour pressures of pure benzene and o-xylene at the given temperature using the Antoine constants provided. By knowing the total pressure and partial pressures contributed by benzene and o-xylene, we can apply Dalton's Law to find the mole fractions in the vapour phase, and from there use the molecular weights to convert to mass fractions.
The mass fraction of benzene in the liquid phase (x_B) and in the vapour phase (y_B) depends on the equilibrium established at 225°C and are determined through iteration because the system includes two unknowns.