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Question: Answered & Verified by Expert
Liquids A and B form an ideal solution in the entire composition range. At 350K, the vapour pressure of pure A and pure B are 7×103Pa and 12×103Pa , respectively. The composition of the vapour in equilibrium with a solution containing 40 mole percent of A at this temperature is:
ChemistrySolutionsJEE MainJEE Main 2019 (10 Jan Shift 1)
Options:
  • A xA=0.4;xB=0.6
  • B xA=0.76;xB=0.24
  • C xA=0.28;xB=0.72
  • D xA=0.37;xB=0.63
Solution:
1822 Upvotes Verified Answer
The correct answer is: xA=0.28;xB=0.72
Since, PA0=7×103Pa;PB0=12×103Pa and XA=0.4 X B =10.4=0.6

According to Raoult's Law: PT=PA0XA+PB0XB

PT=7×1030.4+12×1030.6

PT=10×103Pa

Now, PA0XA=PTxA

xA=PA0XAPT=7×103×0.41040.28

xB=1-xA1-0.280.72

 

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