If the mass of absorbent increased by 0.24 g and the mass of pure solvent (water) decreased by 0.02 — Solutions and Colligative Properties Chemistry Question

💡 Solution & Explanation

The loss in solvent mass is proportional to $(P^\circ - P)$, and the increase in absorbent mass is proportional to $P^\circ$. Thus, relative lowering $(P^\circ - P) / P^\circ = 0.02 / 0.24 = 1/12$. Using Raoult's law: $n / (n + N) = 1/12 \implies N = 11n \implies n/N = 1/11$. Thus, $(W_s / 180) / (W_w / 18) = W_s / (10 W_w) = 1/11 \implies W_s / W_w = 10 / 11$. Mass percent $= (W_s / (W_s + W_w)) \times 100 = (10 / 21) \times 100 = 1000/21\%$. Therefore, correct answer is A.