The vapour pressure of pure liquids A and B are 450 and 700 mm Hg at 350 K respectively. Find out the composition of the liquid mixture if total vapour pressure is 600 mm Hg. Also find the composition of the vapour phase.

Solution

$It is given that : p_{A}^{°} = 450 mm of Hg p_{B}^{0} = 700 mm of Hg p_{total} = 600 mm of Hg from Raoult' s law, we have : p_{A} = p_{A}^{°} x_{A} p_{B} = p_{B}^{0} x_{B} = p_{B}^{°} (1 - x_{A}) therefore, total pressure, p_{total} = p_{A} + p_{B} \Rightarrow p_{total} = p_{A}^{°} x_{A} + p_{B}^{°} (1 - x_{A}) \Rightarrow p_{total} = p_{A}^{°} x_{A} + p_{B}^{°} - p_{B}^{0} x_{A} \Rightarrow p_{total} = (p_{A}^{°} - p_{B}^{°}) x_{A} + p_{B}^{°} \Rightarrow 600 = (450 - 750) x_{A} + 700 \Rightarrow - 100 = - 250 x_{A} \Rightarrow x_{A} = 0.4 therefore, x_{B} = 1 - x_{A} = 1 - 0.4 = 0.6 Now, p_{A} = p_{A}^{°} x_{A} = 450 \times 0.4 = 180 mm of Hg p_{B} = p_{B}^{0} x_{B} = 700 \times 0.6 = 420 mm of Hg Now, fraction of liquid A = \frac{p_{A}}{p_{A +} p_{B}} = \frac{180}{180 + 420} = \frac{180}{600} = 0.30$

mole fraction of liquid b = 1-0.30 = 0.70

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Solutions

The vapour pressure of pure liquids A and B are 450 and 700 mm Hg at 350 K respectively. Find out the composition of the liquid mixture if total vapour pressure is 600 mm Hg. Also find the composition of the vapour phase.

Some More Questions From Solutions Chapter

Calculate the osmotic pressure in pascals exerted by a solution prepared by dissolving 1.0 g of polymer of molar mass 185,000 in 450 mL at 37⁰C.

Suppose a solid solution is formed between two substances, one whose particles are very large and the other whose particles are very small. What kind of solid solution is this likely to be?

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Solutions

The vapour pressure of pure liquids A and B are 450 and 700 mm Hg at 350 K respectively. Find out the composition of the liquid mixture if total vapour pressure is 600 mm Hg. Also find the composition of the vapour phase.

Some More Questions From Solutions Chapter

Calculate the osmotic pressure in pascals exerted by a solution prepared by dissolving 1.0 g of polymer of molar mass 185,000 in 450 mL at 370C.

Suppose a solid solution is formed between two substances, one whose particles are very large and the other whose particles are very small. What kind of solid solution is this likely to be?

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

Calculate the osmotic pressure in pascals exerted by a solution prepared by dissolving 1.0 g of polymer of molar mass 185,000 in 450 mL at 37⁰C.