If 0.1 M solution of NaCl has same osmotic pressure as 0.1 M solution of , the degree of dissociatio — Solutions and Colligative Properties Chemistry Question

💡 Solution & Explanation

Since both solutions are isotonic and have the same concentration, their van't Hoff factors must be equal. Assuming NaCl completely dissociates into 2 ions, $i_{\text{NaCl}} = 2$. For $\text{CaCl}_2$ (which yields 3 ions), $i = 1 + (n-1)\alpha = 1 + 2\alpha$. Equating them gives $1 + 2\alpha = 2 \Rightarrow 2\alpha = 1 \Rightarrow \alpha = 0.5$. Therefore, correct answer is A.