---
title: "A student determines the concentration of a monoprotic acid, \\(\\text{HA(aq)}\\), by titrating a \\(25.00\\text{ mL}\\) sample with \\(0.1000\\text{ M}\\) \\(\\text{NaOH(aq)}\\). The endpoint is assumed to coincide with the equivalence point.  Before each trial, the student rinses the buret with deionized water, drains it, and then fills it directly with the \\(\\text{NaOH(aq)}\\) titrant. A small, reproducible volume of water remains in the buret and mixes with the titrant. The student calculates the acid concentration using the labeled \\(0.1000\\text{ M}\\) titrant concentration and the recorded buret volume.  How does rinsing the buret only with deionized water affect the calculated concentration of \\(\\text{HA}\\)?"
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url: "https://nerd-notes.com/ubq/119507/"
date_modified: "2026-08-19T12:40:54+00:00"
---

# A student determines the concentration of a monoprotic acid, \(\text{HA(aq)}\), by titrating a \(25.00\text{ mL}\) sample with \(0.1000\text{ M}\) \(\text{NaOH(aq)}\). The endpoint is assumed to coincide with the equivalence point.

Before each trial, the student rinses the buret with deionized water, drains it, and then fills it directly with the \(\text{NaOH(aq)}\) titrant. A small, reproducible volume of water remains in the buret and mixes with the titrant. The student calculates the acid concentration using the labeled \(0.1000\text{ M}\) titrant concentration and the recorded buret volume.

How does rinsing the buret only with deionized water affect the calculated concentration of \(\text{HA}\)?

A student determines the concentration of a monoprotic acid, \(\text{HA(aq)}\), by titrating a \(25.00\text{ mL}\) sample with \(0.1000\text{ M}\) \(\text{NaOH(aq)}\). The endpoint is assumed to coincide with the equivalence point.

Before each trial, the student rinses the buret with deionized water, drains it, and then fills it directly with the \(\text{NaOH(aq)}\) titrant. A small, reproducible volume of water remains in the buret and mixes with the titrant. The student calculates the acid concentration using the labeled \(0.1000\text{ M}\) titrant concentration and the recorded buret volume.

How does rinsing the buret only with deionized water affect the calculated concentration of \(\text{HA}\)?

- **A.** The calculated concentration is too low because the residual water lowers the concentration of the \(\text{NaOH(aq)}\) delivered from the buret.
- **B.** The calculated concentration is too high because the residual water dilutes the \(\text{NaOH(aq)}\), so a larger buret volume is required to deliver the equivalence-point moles of \(\text{OH}^{-}\text{(aq)}\), and that larger volume is multiplied by \(0.1000\text{ M}\).
- **C.** The calculated concentration is too high because the residual water dilutes the acid in the flask, so more titrant must be added to neutralize the acid.
- **D.** The calculated concentration is unchanged because adding deionized water does not change the number of moles of \(\text{HA}\) originally present in the flask.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119507/*