A) 35.8 torr and 0.280
B) 38.0 torr and 0.589
C) 30.5 torr and 0.389
D) 30.5 torr and 0.480
Correct Answer: B
Solution :
[b] Total V.P. of solution \[=P_{A}^{{}^\circ }{{x}_{A}}+P_{B}^{{}^\circ }{{x}_{B}}\] Given, \[P_{A}^{{}^\circ }\ =74.7\,torr,P_{B}^{{}^\circ }=22.3torr\] \[{{n}_{benzene}}=1.5mol,\,\,{{n}_{toluene}}=3.5\,mol\] \[{{n}_{solution}}=1.5+3.5\,=5mol\] \[{{x}_{A}}=\frac{{{n}_{benzene}}}{{{n}_{solution}}}=\frac{1.5}{5}\] Total V.P. of solution \[=\left( \frac{1.5}{5}\times 74.7+\frac{3.5}{5}\times 22.3 \right)\] torr \[=\left( 22.4+15.6 \right)torr=38\text{ }torr\] Mole fraction of benzene in vapour form \[=\frac{22.4}{38}=0.589\]You need to login to perform this action.
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