---
title: "A student titrates a 20.0 mL sample of a diprotic acid solution, \\(\\text{H}_2\\text{A(aq)}\\), with a standardized \\(0.100 \\text{ M NaOH(aq)}\\) solution using phenolphthalein as an indicator. The net ionic equation for the reaction that occurs during the titration is shown below.  \\[\\text{H}_2\\text{A(aq)} + 2\\text{OH}^-\\text{(aq)} \\rightarrow \\text{A}^{2-}\\text{(aq)} + 2\\text{H}_2\\text{O(l)}\\]  The initial buret reading of \\(0.100 \\text{ M NaOH(aq)}\\) is 5.00 mL. At the pale pink endpoint, the final buret reading is 45.00 mL. What is the molarity of the \\(\\text{H}_2\\text{A(aq)}\\) sample?"
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url: "https://nerd-notes.com/ubq/119366/"
date_modified: "2026-08-19T12:40:00+00:00"
---

# A student titrates a 20.0 mL sample of a diprotic acid solution, \(\text{H}_2\text{A(aq)}\), with a standardized \(0.100 \text{ M NaOH(aq)}\) solution using phenolphthalein as an indicator. The net ionic equation for the reaction that occurs during the titration is shown below.

\[\text{H}_2\text{A(aq)} + 2\text{OH}^-\text{(aq)} \rightarrow \text{A}^{2-}\text{(aq)} + 2\text{H}_2\text{O(l)}\]

The initial buret reading of \(0.100 \text{ M NaOH(aq)}\) is 5.00 mL. At the pale pink endpoint, the final buret reading is 45.00 mL. What is the molarity of the \(\text{H}_2\text{A(aq)}\) sample?

A student titrates a 20.0 mL sample of a diprotic acid solution, \(\text{H}_2\text{A(aq)}\), with a standardized \(0.100 \text{ M NaOH(aq)}\) solution using phenolphthalein as an indicator. The net ionic equation for the reaction that occurs during the titration is shown below.

\[\text{H}_2\text{A(aq)} + 2\text{OH}^-\text{(aq)} \rightarrow \text{A}^{2-}\text{(aq)} + 2\text{H}_2\text{O(l)}\]

The initial buret reading of \(0.100 \text{ M NaOH(aq)}\) is 5.00 mL. At the pale pink endpoint, the final buret reading is 45.00 mL. What is the molarity of the \(\text{H}_2\text{A(aq)}\) sample?

- **A.** \(0.0333 \text{ M}\)
- **B.** \(0.0667 \text{ M}\)
- **C.** \(0.100 \text{ M}\)
- **D.** \(0.200 \text{ M}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119366/*