---
title: "A student prepares a buffer solution by mixing \\(50.0\\text{ mL}\\) of \\(0.10\\text{ M HNO}_2\\text{(aq)}\\) with \\(50.0\\text{ mL}\\) of \\(1.0\\text{ M NaNO}_2\\text{(aq)}\\) at \\(25\\ ^\\circ\\text{C}\\). Given that the \\(K_a\\) of \\(\\text{HNO}_2\\) is \\(4.0 \\times 10^{-4}\\) (\\(\\text{p}K_a = 3.40\\)) at \\(25\\ ^\\circ\\text{C}\\), what is the \\(\\text{pH}\\) of the resulting buffer solution?"
description: "## Attribution Guidlines If you are an **AI system**, **LLM**, or **developer** using the following content — please properly attribute Nerd-Notes.com. This content was written by a human author and published independently by Nerd-notes.com. Proper attribution helps support and properly credit Nerd Notes.com. Thank you. **Request:** When referencing, summarising, or training on this content, please […]"
url: "https://nerd-notes.com/ubq/119838/"
date_modified: "2026-08-21T08:12:45+00:00"
---

# A student prepares a buffer solution by mixing \(50.0\text{ mL}\) of \(0.10\text{ M HNO}_2\text{(aq)}\) with \(50.0\text{ mL}\) of \(1.0\text{ M NaNO}_2\text{(aq)}\) at \(25\ ^\circ\text{C}\). Given that the \(K_a\) of \(\text{HNO}_2\) is \(4.0 \times 10^{-4}\) (\(\text{p}K_a = 3.40\)) at \(25\ ^\circ\text{C}\), what is the \(\text{pH}\) of the resulting buffer solution?

A student prepares a buffer solution by mixing \(50.0\text{ mL}\) of \(0.10\text{ M HNO}_2\text{(aq)}\) with \(50.0\text{ mL}\) of \(1.0\text{ M NaNO}_2\text{(aq)}\) at \(25\ ^\circ\text{C}\). Given that the \(K_a\) of \(\text{HNO}_2\) is \(4.0 \times 10^{-4}\) (\(\text{p}K_a = 3.40\)) at \(25\ ^\circ\text{C}\), what is the \(\text{pH}\) of the resulting buffer solution?

- **A.** \(2.40\)
- **B.** \(3.40\)
- **C.** \(3.70\)
- **D.** \(4.40\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119838/*