The vapour pressures of two volatile liquids A and B at 25°C are 50 Torr and 100 Torr, respectively. If the liquid mixture contains 0.3 mole fraction of A, then the mole fraction of liquid B in the va

Question

The vapour pressures of two volatile liquids A and B at 25°C are 50 Torr and 100 Torr, respectively. If the liquid mixture contains 0.3 mole fraction of A, then the mole fraction of liquid B in the vapour phase is . The value of x is

Canvas Classes · Accepted Answer

Strategy:
 Mole fraction in the vapour phase () can be calculated from the partial pressures using Dalton's Law (). Partial pressures themselves are determined by Raoult's Law ().

Step 1: Determine liquid mole fractions
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Step 2: Calculate partial pressures (Raoult's Law)
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Step 3: Calculate total pressure ()

Step 4: Find the mole fraction of B in the vapour phase ()

Comparing with the given form , we find .

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