---
title: "A student prepares two separate \\(1.0 \\text{ L}\\) buffer solutions using a weak monoprotic acid, \\(\\text{HA}\\) (\\(\\text{p}K_a = 5.00\\)), and its conjugate base salt, \\(\\text{NaA}\\). Buffer 1 contains \\(0.40 \\text{ mol}\\) of \\(\\text{HA}\\) and \\(0.40 \\text{ mol}\\) of \\(\\text{NaA}\\). Buffer 2 contains \\(0.20 \\text{ mol}\\) of \\(\\text{HA}\\) and \\(0.20 \\text{ mol}\\) of \\(\\text{NaA}\\).  A \\(0.10 \\text{ mol}\\) sample of \\(\\text{HCl}(g)\\) is dissolved into each buffer solution with negligible change in total volume. Which of the following correctly gives the final ratio \\(\\dfrac{[\\text{A}^-]}{[\\text{HA}]}\\) for each buffer and compares the magnitudes of the \\(\\text{pH}\\) changes (\\(\\Delta\\text{pH} = |\\text{pH}_{\\text{final}} – \\text{pH}_{\\text{initial}}|\\))?"
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/123852/"
date_modified: "2026-09-28T12:30:34+00:00"
---

# A student prepares two separate \(1.0 \text{ L}\) buffer solutions using a weak monoprotic acid, \(\text{HA}\) (\(\text{p}K_a = 5.00\)), and its conjugate base salt, \(\text{NaA}\). Buffer 1 contains \(0.40 \text{ mol}\) of \(\text{HA}\) and \(0.40 \text{ mol}\) of \(\text{NaA}\). Buffer 2 contains \(0.20 \text{ mol}\) of \(\text{HA}\) and \(0.20 \text{ mol}\) of \(\text{NaA}\).

A \(0.10 \text{ mol}\) sample of \(\text{HCl}(g)\) is dissolved into each buffer solution with negligible change in total volume. Which of the following correctly gives the final ratio \(\dfrac{[\text{A}^-]}{[\text{HA}]}\) for each buffer and compares the magnitudes of the \(\text{pH}\) changes (\(\Delta\text{pH} = |\text{pH}_{\text{final}} – \text{pH}_{\text{initial}}|\))?

A student prepares two separate \(1.0 \text{ L}\) buffer solutions using a weak monoprotic acid, \(\text{HA}\) (\(\text{p}K_a = 5.00\)), and its conjugate base salt, \(\text{NaA}\). Buffer 1 contains \(0.40 \text{ mol}\) of \(\text{HA}\) and \(0.40 \text{ mol}\) of \(\text{NaA}\). Buffer 2 contains \(0.20 \text{ mol}\) of \(\text{HA}\) and \(0.20 \text{ mol}\) of \(\text{NaA}\).

A \(0.10 \text{ mol}\) sample of \(\text{HCl}(g)\) is dissolved into each buffer solution with negligible change in total volume. Which of the following correctly gives the final ratio \(\dfrac{[\text{A}^-]}{[\text{HA}]}\) for each buffer and compares the magnitudes of the \(\text{pH}\) changes (\(\Delta\text{pH} = |\text{pH}_{\text{final}} - \text{pH}_{\text{initial}}|\))?

- **A.** In Buffer 1, \(\dfrac{[\text{A}^-]}{[\text{HA}]} = \dfrac{3}{4}\); in Buffer 2, \(\dfrac{[\text{A}^-]}{[\text{HA}]} = \dfrac{1}{2}\); and \(\Delta\text{pH}_2 < \Delta\text{pH}_1\).
- **B.** In Buffer 1, \(\dfrac{[\text{A}^-]}{[\text{HA}]} = \dfrac{3}{5}\); in Buffer 2, \(\dfrac{[\text{A}^-]}{[\text{HA}]} = \dfrac{1}{3}\); and \(\Delta\text{pH}_2 > \Delta\text{pH}_1\).
- **C.** In Buffer 1, \(\dfrac{[\text{A}^-]}{[\text{HA}]} = \dfrac{3}{5}\); in Buffer 2, \(\dfrac{[\text{A}^-]}{[\text{HA}]} = \dfrac{1}{3}\); and \(\Delta\text{pH}_2 = \Delta\text{pH}_1\).
- **D.** In Buffer 1, \(\dfrac{[\text{A}^-]}{[\text{HA}]} = \dfrac{3}{4}\); in Buffer 2, \(\dfrac{[\text{A}^-]}{[\text{HA}]} = \dfrac{1}{2}\); and \(\Delta\text{pH}_2 > \Delta\text{pH}_1\).

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123852/*