---
title: "A student titrates a \\(25.0\\text{ mL}\\) sample of a weak monoprotic acid, \\(\\text{HA(aq)}\\), with \\(0.100\\text{ M NaOH(aq)}\\). The \\(\\text{pH}\\) of the mixture is measured after successive additions of titrant, as shown in the table below.  | Volume of \\(0.100\\text{ M NaOH}\\) added (mL) | \\(\\text{pH}\\) | | :—: | :—: | | \\(0.0\\) | \\(2.88\\) | | \\(6.0\\) | \\(4.38\\) | | \\(12.0\\) | \\(4.76\\) | | \\(18.0\\) | \\(5.24\\) | | \\(23.0\\) | \\(5.85\\) | | \\(24.0\\) | \\(8.80\\) | | \\(25.0\\) | \\(11.60\\) | | \\(30.0\\) | \\(12.30\\) |  Based on the data in the table, which of the following identifies the volume of \\(\\text{NaOH(aq)}\\) added at which the solution exhibits its maximum buffering capacity, along with the correct justification?"
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date_modified: "2026-09-28T12:30:20+00:00"
---

# A student titrates a \(25.0\text{ mL}\) sample of a weak monoprotic acid, \(\text{HA(aq)}\), with \(0.100\text{ M NaOH(aq)}\). The \(\text{pH}\) of the mixture is measured after successive additions of titrant, as shown in the table below.

| Volume of \(0.100\text{ M NaOH}\) added (mL) | \(\text{pH}\) |
| :—: | :—: |
| \(0.0\) | \(2.88\) |
| \(6.0\) | \(4.38\) |
| \(12.0\) | \(4.76\) |
| \(18.0\) | \(5.24\) |
| \(23.0\) | \(5.85\) |
| \(24.0\) | \(8.80\) |
| \(25.0\) | \(11.60\) |
| \(30.0\) | \(12.30\) |

Based on the data in the table, which of the following identifies the volume of \(\text{NaOH(aq)}\) added at which the solution exhibits its maximum buffering capacity, along with the correct justification?

A student titrates a \(25.0\text{ mL}\) sample of a weak monoprotic acid, \(\text{HA(aq)}\), with \(0.100\text{ M NaOH(aq)}\). The \(\text{pH}\) of the mixture is measured after successive additions of titrant, as shown in the table below.

| Volume of \(0.100\text{ M NaOH}\) added (mL) | \(\text{pH}\) |
| :---: | :---: |
| \(0.0\) | \(2.88\) |
| \(6.0\) | \(4.38\) |
| \(12.0\) | \(4.76\) |
| \(18.0\) | \(5.24\) |
| \(23.0\) | \(5.85\) |
| \(24.0\) | \(8.80\) |
| \(25.0\) | \(11.60\) |
| \(30.0\) | \(12.30\) |

Based on the data in the table, which of the following identifies the volume of \(\text{NaOH(aq)}\) added at which the solution exhibits its maximum buffering capacity, along with the correct justification?

- **A.** \(6.0\text{ mL}\), because the ratio of \([\text{HA}]\) to \([\text{A}^-]\) is greatest in the initial buffer region, providing maximum resistance to added base.
- **B.** \(12.0\text{ mL}\), because the equivalence point occurs at \(24.0\text{ mL}\) and half-neutralization results in equal concentrations of \(\text{HA}\) and \(\text{A}^-\).
- **C.** \(24.0\text{ mL}\), because the concentration of \([\text{A}^-]\) reaches its maximum, allowing the solution to neutralize the greatest amount of added acid.
- **D.** \(24.0\text{ mL}\), because the large change in \(\text{pH}\) per volume of titrant added indicates that the acid-base equilibrium is most active.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123796/*