Solutions Question 252
Question: The vapour pressure of n-hexane at 350 K is 840 torr and that of cyclohexane is 600 torr. Mote fraction of hexane in the mixture that boils at 350 K and 1 atm pressure assuming ideal behaviour is
Options:
A) 0.67
B) 0.80
C) 0.50
D) 2.2
Show Answer
Answer:
Correct Answer: A
Solution:
Mixture boils at 1 atm and 350 K Thus, total vapour pressure is 1 atm =760 torr (h) used for hexane and (ch) for cyclohexane. $ p_{total}=p_h^{0}{\chi_{h}}^{0}+p_ch^{0}{\chi_{ch}}\Rightarrow p_{total} $
$ =p_h^{0}{\chi_{h}}+p_ch^{0}(1-{\chi_{h}}) $
$ 760=840{\chi_{h}}+600(1-{\chi_{h}}) $
$ \therefore {\chi_{h}}=0.67 $
