The concentration of acetate ions in 1 M acetic acid () solution containing 0.1 M – HCl is — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

Due to the common ion effect from the strong acid HCl, the hydrogen ion concentration is determined entirely by HCl: $[\text{H}^+] \approx 0.1\text{ M}$. Using the $K_a$ expression for acetic acid: $K_a = \frac{[\text{CH}_3\text{COO}^-][\text{H}^+]}{[\text{CH}_3\text{COOH}]} \implies 2 \times 10^{-5} = \frac{[\text{CH}_3\text{COO}^-](0.1)}{1.0}$. Solving for $[\text{CH}_3\text{COO}^-]$ gives $2 \times 10^{-4}\text{ M}$.