An aqueous solution of sucrose is 0.5 molal. What is the vapour pressure of water above this solutio — Solutions and Colligative Properties Chemistry Question

💡 Solution & Explanation

0.5 molal means 0.5 moles solute in 1 kg (55.55 moles) of water. $X_{\text{water}} = \frac{55.55}{55.55 + 0.5} = \frac{55.55}{56.05} = 0.991$. Vapour pressure $P = 25.0 \times 0.991 = 24.775 \approx 24.8$ mm Hg. Therefore, correct answer is A.