The vapors pressures pure liquids |LIQUIDSOLUTIONJEEMain2019

JEE MAI 2019

08-04-2019 S1

Question

The vapour pressures of pure liquids A and B are 400 and 600 mmHg, respectively at 298 K. On mixing the two liquids, the sum of their initial volumes is equal to the volume of the final mixture. The mole fraction of liquid B is 0.5 in the mixture. The vapour pressure of the final solution, the mole fractions of components A and B in vapour phase, respectively are :

Select the correct option:

500 mmHg, 0.4, 0.6

500 mmHg, 0.5, 0.5

450 mmHg, 0.4, 0.6

450 mmHg, 0.5, 0.5

✓ Correct! Well done.

✗ Incorrect. Try again or view the solution.

Solution

$\begin{aligned} & P=x_B p_B^0+x_A p_A^0 \\ & =0.5 \times 600+0.5 \times 400=300+200=500 \\ & p_B=y_B P_{\text {Total }} \\ & y_B=\frac{p_B}{P_{\text {Total }}}=\frac{300}{500}=\frac{3}{5}=0.6 \\ & y_A=\frac{p_A}{P_{\text {Total }}}=\frac{200}{500}=\frac{2}{5}=0.4\end{aligned}$

Question Tags

JEE Main

Chemistry

Easy

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