---
title: "A student prepares a buffer solution containing equal molar amounts of a weak acid, \\(\\text{HA}\\), and its conjugate base, \\(\\text{A}^-\\). Which of the following statements best explains why an equimolar mixture of \\(\\text{HA}\\) and \\(\\text{A}^-\\) achieves maximum buffer capacity for a fixed total solute concentration?"
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url: "https://nerd-notes.com/ubq/119305/"
date_modified: "2026-08-19T12:39:44+00:00"
---

# A student prepares a buffer solution containing equal molar amounts of a weak acid, \(\text{HA}\), and its conjugate base, \(\text{A}^-\). Which of the following statements best explains why an equimolar mixture of \(\text{HA}\) and \(\text{A}^-\) achieves maximum buffer capacity for a fixed total solute concentration?

A student prepares a buffer solution containing equal molar amounts of a weak acid, \(\text{HA}\), and its conjugate base, \(\text{A}^-\). Which of the following statements best explains why an equimolar mixture of \(\text{HA}\) and \(\text{A}^-\) achieves maximum buffer capacity for a fixed total solute concentration?

- **A.** It provides maximum resistance to pH changes from both added acid and added base, because equal amounts of \(\text{HA}\) (to react with added \(\text{OH}^-\)) and \(\text{A}^-\) (to react with added \(\text{H}_3\text{O}^+\)) are present.
- **B.** It provides maximum resistance to pH changes from both added acid and added base, because \(\text{HA}\) neutralizes added \(\text{H}_3\text{O}^+\) while \(\text{A}^-\) neutralizes added \(\text{OH}^-\).
- **C.** It completely prevents any change in pH when acid or base is added, because \(\text{HA}\) and \(\text{A}^-\) continuously neutralize each other in solution.
- **D.** It completely prevents any change in pH when acid or base is added, because an equimolar buffer solution always has a neutral pH equal to 7.0.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119305/*