---
title: "A \\(25.0\\text{ mL}\\) sample of a \\(0.10\\text{ M}\\) solution of a weak monoprotic acid, \\(\\text{HA}\\) (\\(K_a = 1.0 \\times 10^{-5}\\)), is represented in the diagram above, where each \\(\\text{HA}\\) particle represents \\(0.000625\\text{ mol}\\) of acid. Water molecules and the autoionization of water are omitted for clarity. The sample is titrated with \\(0.10\\text{ M } \\text{NaOH(aq)}\\).  Which of the following particulate diagrams best represents the major species present in the reaction flask after \\(37.5\\text{ mL}\\) of \\(0.10\\text{ M } \\text{NaOH(aq)}\\) has been added?"
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url: "https://nerd-notes.com/ubq/119845/"
date_modified: "2026-08-21T08:12:55+00:00"
---

# A \(25.0\text{ mL}\) sample of a \(0.10\text{ M}\) solution of a weak monoprotic acid, \(\text{HA}\) (\(K_a = 1.0 \times 10^{-5}\)), is represented in the diagram above, where each \(\text{HA}\) particle represents \(0.000625\text{ mol}\) of acid. Water molecules and the autoionization of water are omitted for clarity. The sample is titrated with \(0.10\text{ M } \text{NaOH(aq)}\).

Which of the following particulate diagrams best represents the major species present in the reaction flask after \(37.5\text{ mL}\) of \(0.10\text{ M } \text{NaOH(aq)}\) has been added?

A \(25.0\text{ mL}\) sample of a \(0.10\text{ M}\) solution of a weak monoprotic acid, \(\text{HA}\) (\(K_a = 1.0 \times 10^{-5}\)), is represented in the diagram above, where each \(\text{HA}\) particle represents \(0.000625\text{ mol}\) of acid. Water molecules and the autoionization of water are omitted for clarity. The sample is titrated with \(0.10\text{ M } \text{NaOH(aq)}\).

Which of the following particulate diagrams best represents the major species present in the reaction flask after \(37.5\text{ mL}\) of \(0.10\text{ M } \text{NaOH(aq)}\) has been added?

![A rectangular diagram consists of a legend box at the top and a square beaker container below. The legend box defines one symbol: a pair of touching circles consisting of one small open white circle attached to one larger light-gray circle represents \(\text{HA}\). Inside the square beaker container, exactly 4 identical \(\text{HA}\) pairs are evenly dispersed in the space. Each \(\text{HA}\) pair consists of the small white circle directly touching the larger light-gray circle. No separate unattached circles or ions are present in the container. No other particles, labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/diagram-stem-ha-1787299974-ESseEd.jpg)

- **A.** Diagram A
- **B.** Diagram B
- **C.** Diagram C
- **D.** Diagram D

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119845/*