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4 years ago

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Two volatile substances, A and B are dissolved in one another and the resulting solution has a vapor pressure of 137 torr. If th

e mole fraction of B is 0.230 and the vapor pressure of pure B is 162 torr, what is the vapor pressure of pure A in torr?

1 answer:

liq [111]4 years ago

5 0

Answer:

Vapor pressure of pure A is 129.5torr

Explanation:

When two or more liquids produce an ideal solution, the vapour pressure of the mixture follows the equation (Raoult's law):

$P_T = P_aX_a + P_bX_b$

<em>Where P is vapour pressure and X mole fraction of liquids A and B. Pt is the pressure of the solution</em>

<em />

As mole fraction of B is 0.230, mole fraction of A is:

$1 =X_a+X_b\\1=X_a+0.230\\X_a=0.77$

Computing in Raoult's law with the given values:

$137 torr= P_a0.77 + 162torr*0.23\\137 torr = 0.77P_a+37.26torr\\99.74torr = 0.77P_a\\P_a=129.5torr$

<h3>Vapor pressure of pure A is 129.5torr</h3>

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$Total~volume=50mL+10mL=60mL$

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