A aqueous solution of Potassium ferrocyanide, , is supposed to be exactly dissociated at room temper — Solutions and Colligative Properties Chemistry Question

💡 Solution & Explanation

For $K_4[Fe(CN)_6]$, $n=5$. $i = 1 + \alpha(n-1) = 1 + 0.4(4) = 2.6$. Isotonic means $i_1 C_1 = i_2 C_2$. $2.6 \times 1\text{ M} = 1 \times C_A \implies C_A = 2.6\text{ M}$. A $20\% \text{ w/v}$ solution is $200\text{ g/L}$. Molar mass $M_A = \frac{200}{2.6} \approx 76.92\text{ g mol}^{-1}$.