The vapour pressure of a solution of two liquids, A (P° = 80 mm, X = 0.4) and B (P° = 120 mm, X = 0. — Solutions and Colligative Properties Chemistry Question

💡 Solution & Explanation

For an ideal solution: P_ideal = P_A^o * X_A + P_B^o * X_B = 80 * 0.4 + 120 * 0.6 = 32 + 72 = 104 mm. The observed vapour pressure (100 mm) is less than the expected ideal vapour pressure (104 mm), which indicates a negative deviation from Raoult's law.