Question

Vapour pressures of pure liquids 'A' and 'D' are 500 mm Hg and 800 mm Hg, respectively.The binary solution of ’A’ and ’D’ boils at 50◦C and 700 mm Hg pressure.The mole percentage of D in the solution is:

• A. 33.33 mole percent
• B. 66.67 mole percent
• C. 25.75 mole percent
• D. 75.25 mole percent

Answer 1

Answer: (B)

66.67 mole percent

Answer 2

Using Raoult’s Law, the total vapour pressure of the solution is calculated, and the mole fraction of D is 66.67$\%$.