The vapour pressure of pure benzene at 50 C° is 268 torr. How many mol of non-volatile solute per mol of benzene is required to prepare a solution of benzene having a vapour pressure of 167 torr at 50 C° .
Correct answer: B. 0.605
- A. 0.377
- B. 0.605
- C. 0.623
- D. 0.395
Explanation
By Raoult's law x_benzene = P/P° = 167/268 = 0.623, so x_solute = 0.377. Moles of solute per mole of benzene = x_solute / x_benzene = 0.377 / 0.623 ≈ 0.605.
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