If the experiment is performed with aqueous solution () prepared by dissolving 1 mole of in 17 mole — Solutions and Colligative Properties Chemistry Question
Question
If the experiment is performed with aqueous $\text{AlCl}_3$ solution ($\alpha = 0.8$) prepared by dissolving 1 mole of $\text{AlCl}_3$ in 17 mole water and the decrease in the mass of solution in the experiment is found to be 0.18 g, then the increase in the mass of absorbent should be
💡 Solution & Explanation
$\text{AlCl}_3$ dissociates into 4 ions, so $i = 1 + 3(0.8) = 3.4$. Effective moles $n = 3.4 \times 1 = 3.4$. Moles of water $N = 17$. Decrease in mass of solution $\propto P$. Increase in mass of absorbent $\propto P^\circ$. Ratio is $P / P^\circ = N / (N + n) = 17 / (17 + 3.4) = 17 / 20.4 = 5 / 6$. Let $x$ be the mass increase in absorbent. $0.18 / x = 5 / 6 \implies x = 0.18 \times 6 / 5 = 1.08 / 5 = 0.216 \text{ g}$. Therefore, correct answer is A.