Liquids A and B form an ideal solution in the entire composition range. At 350 K, the vapour pressures of pure A and pure B are 7 × 103 Pa and 12 × 103 Pa, respectively. The composition of the vapour in equilibrium with a solution containing 40 mole percent of A at this temperature is:

Engineering

Chemistry

Raoult Law and Vapour Pressure

Question

Liquids A and B form an ideal solution in the entire composition range. At 350 K, the vapour pressures of pure A and pure B are 7 × 10³ Pa and 12 × 10³ Pa, respectively. The composition of the vapour in equilibrium with a solution containing 40 mole percent of A at this temperature is:

x_A = 0.76 ; x_B = 0.24

x_A = 0.4 ; x_B = 0.6

x_A = 0.37; x_B = 0.63

x_A = 0.28 ; x_B = 0.72

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P_solution = 7 × 10³ (0.4) + 12 × 10³ (0.6)

= 10⁴ Pa

In vapour phase,

x_A = $\frac{7 \times 10^{3} \times 0 .4}{10^{4}}$ = 0.28

x_B = 1 – x_A = 0.72