A volume of 10 ml of a strong acid solution of pH = 2.0 are mixed with 990 ml of a buffer solution o — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

The $10\text{ ml}$ of strong acid ($\text{pH} = 2.0 \implies [\text{H}^+] = 0.01\text{ M}$) contains an extremely small amount of $\text{H}^+$ ($0.1\text{ mmol}$). When added to a massive $990\text{ ml}$ volume of a buffer solution, the buffer easily neutralizes the added $\text{H}^+$ with practically zero shift in the $[\text{Salt}]/[\text{Acid}]$ ratio. Therefore, the pH remains unchanged at roughly 4.0.