---
title: "A student tests the response of a water-quality calibration buffer to added strong base. The buffer and added solution have the following properties at \\(25^\\circ\\text{C}\\).  | Solution | Volume | Solute concentrations | |—|—:|—| | Buffer | \\(50.0\\text{ mL}\\) | \\(0.100\\text{ M NH}_3\\) and \\(0.500\\text{ M NH}_4\\text{Cl}\\) | | Added solution | \\(50.0\\text{ mL}\\) | \\(0.100\\text{ M NaOH}\\) |  For \\(\\text{NH}_4^+\\text{(aq)}\\), \\(pK_a=9.25\\). Assume that the volumes are additive and that \\(\\log 2=0.30\\). What is the pH of the solution after the solutions are mixed?"
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url: "https://nerd-notes.com/ubq/119469/"
date_modified: "2026-08-19T12:40:35+00:00"
---

# A student tests the response of a water-quality calibration buffer to added strong base. The buffer and added solution have the following properties at \(25^\circ\text{C}\).

| Solution | Volume | Solute concentrations |
|—|—:|—|
| Buffer | \(50.0\text{ mL}\) | \(0.100\text{ M NH}_3\) and \(0.500\text{ M NH}_4\text{Cl}\) |
| Added solution | \(50.0\text{ mL}\) | \(0.100\text{ M NaOH}\) |

For \(\text{NH}_4^+\text{(aq)}\), \(pK_a=9.25\). Assume that the volumes are additive and that \(\log 2=0.30\). What is the pH of the solution after the solutions are mixed?

A student tests the response of a water-quality calibration buffer to added strong base. The buffer and added solution have the following properties at \(25^\circ\text{C}\).

| Solution | Volume | Solute concentrations |
|---|---:|---|
| Buffer | \(50.0\text{ mL}\) | \(0.100\text{ M NH}_3\) and \(0.500\text{ M NH}_4\text{Cl}\) |
| Added solution | \(50.0\text{ mL}\) | \(0.100\text{ M NaOH}\) |

For \(\text{NH}_4^+\text{(aq)}\), \(pK_a=9.25\). Assume that the volumes are additive and that \(\log 2=0.30\). What is the pH of the solution after the solutions are mixed?

- **A.** \(8.55\)
- **B.** \(8.95\)
- **C.** \(9.55\)
- **D.** \(12.70\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119469/*