At $25^{\circ}C,$ the total pressure of an ideal solution obtained by mixing 3 moles of ‘A’ and 2 moles of ‘B’, is 184 torr. What is the vapour pressure (in torr) of pure ‘B’ at the same temperature? (Vapour pressure of pure ‘A’ at $25^{\circ}C$ is 200 torr)

Question

Dr. Abubacker · Accepted Answer

(b)
$P = p_{A}^{\circ}\ \left( \frac{n_{A}}{n_{A} + n_{B}} ight) + p_{B}^{\circ}\left( \frac{n_{B}}{n_{A} + n_{B}} ight)\$
$184 = 200\left( \frac{3}{3 + 2} ight)p_{B}^{\circ}\left( \frac{2}{3 + 2} ight)\ \ \$
$184 = 200 	imes \frac{3}{5} + p_{B}^{\circ} 	imes \frac{2}{5}$
184=200+$p_{B}^{\circ}\frac{2}{5}$
64=$p_{B}^{\circ}\frac{2}{5}$
$p_{B}^{\circ}$=$\frac{64 	imes 5}{2}$ =160 torr

Q. At $25^{\circ}C,$ the total pressure of an ideal solution obtained by mixing 3 moles of ‘A’ and 2 moles of ‘B’, is 184 torr. What is the vapour pressure (in torr) of pure ‘B’ at the same temperature? (Vapour pressure of pure ‘A’ at $25^{\circ}C$ is 200 torr)

Explanation

Reviewed by Dr. Abubacker

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