NEET Solved Paper 2016 Question 35
Question: Which of the following statement about the composition of the vapour over an ideal a 1 : 1 molar mixture of benzene and toluene is correct? Assume that the temperature is constant at $ 25{{,}^{o}}C\text{.} $ (Given : Vapour Pressure Data at $ 25{{,}^{o}}\text{C,} $ benzene = 12.8 kPa, Toluene = 3.85 kPa)
Options:
A) The vapour will contain a higher percentage of benzene
B) The vapour will contain a higher percentage of toluene
C) The vapour will contain equal amounts of benezene and toluene
D) Not enough information is given to make a predication
Show Answer
Answer:
Correct Answer: A
Solution:
- A $ \to $ benzene, $ \to $ toluene 1 : 1 molar mixture of A and B
$ \therefore $ $ x _{A}=\frac{1}{2} $ and $ x _{B}=\frac{1}{2} $ $ P{ _{s}}=P_A^{0}X _{A}+P_B^{0}X _{B} $ $ P _{s}=12.8\times \frac{1}{2}+3.85\times \frac{1}{2,}=8.325,kPa $ $ Y _{A}=\frac{P_A^{0}X _{A}}{P _{s}}=\frac{12.8\times \frac{1}{2}}{8.325}=0.768 $
$ \therefore $ $ Y _{B}=1-Y _{A}=1-0.768=0.232 $ so, the vapour will contain higher percentage of benzene.
