The degree of dissociation of a 0.1 M HCN solution is 0.01%. Its ionisation constant () would be: — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

$\alpha = 0.01\% = 10^{-4}$. For a weak acid, $K_a = C\alpha^2$ (since $\alpha \ll 1$). Thus, $K_a = 0.1 \times (10^{-4})^2 = 0.1 \times 10^{-8} = 10^{-9}$.