---
title: "A student determines the mass percent of sulfate, \\(\\text{SO}_4^{2-}\\), in a sample of solid fertilizer using gravimetric analysis. A \\(1.50\\text{ g}\\) sample of the fertilizer is dissolved in distilled water, and an excess of \\(0.20\\text{ M }\\text{BaCl}_2\\text{(aq)}\\) is added to precipitate all the sulfate ions according to the reaction below.  \\[ \\text{Ba}^{2+}\\text{(aq)} + \\text{SO}_4^{2-}\\text{(aq)} \\rightarrow \\text{BaSO}_4\\text{(s)} \\]  The precipitate is collected on filter paper. However, the student does not allow the filter paper and precipitate to dry completely before recording the final mass. Which of the following best explains how this error affects the calculated mass percent of \\(\\text{SO}_4^{2-}\\) in the fertilizer sample?"
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url: "https://nerd-notes.com/ubq/123630/"
date_modified: "2026-09-28T12:01:50+00:00"
---

# A student determines the mass percent of sulfate, \(\text{SO}_4^{2-}\), in a sample of solid fertilizer using gravimetric analysis. A \(1.50\text{ g}\) sample of the fertilizer is dissolved in distilled water, and an excess of \(0.20\text{ M }\text{BaCl}_2\text{(aq)}\) is added to precipitate all the sulfate ions according to the reaction below.

\[ \text{Ba}^{2+}\text{(aq)} + \text{SO}_4^{2-}\text{(aq)} \rightarrow \text{BaSO}_4\text{(s)} \]

The precipitate is collected on filter paper. However, the student does not allow the filter paper and precipitate to dry completely before recording the final mass. Which of the following best explains how this error affects the calculated mass percent of \(\text{SO}_4^{2-}\) in the fertilizer sample?

A student determines the mass percent of sulfate, \(\text{SO}_4^{2-}\), in a sample of solid fertilizer using gravimetric analysis. A \(1.50\text{ g}\) sample of the fertilizer is dissolved in distilled water, and an excess of \(0.20\text{ M }\text{BaCl}_2\text{(aq)}\) is added to precipitate all the sulfate ions according to the reaction below.

\[ \text{Ba}^{2+}\text{(aq)} + \text{SO}_4^{2-}\text{(aq)} \rightarrow \text{BaSO}_4\text{(s)} \]

The precipitate is collected on filter paper. However, the student does not allow the filter paper and precipitate to dry completely before recording the final mass. Which of the following best explains how this error affects the calculated mass percent of \(\text{SO}_4^{2-}\) in the fertilizer sample?

- **A.** The calculated mass percent will be too low because unevaporated water dissolves a portion of the \(\text{BaSO}_4\text{(s)}\) precipitate, decreasing the mass of solid retained on the filter paper.
- **B.** The calculated mass percent will be too high because residual water increases the measured mass of the precipitate, resulting in an overestimate of the mass of \(\text{SO}_4^{2-}\) in the sample.
- **C.** The calculated mass percent will be too high because the extra mass of water decreases the molar mass of \(\text{BaSO}_4\text{(s)}\) used in the stoichiometric calculation, yielding more calculated moles of \(\text{SO}_4^{2-}\).
- **D.** The calculated mass percent will be too low because the presence of residual water dilutes the solution, which shifts the precipitation reaction backward and decreases the yield of \(\text{BaSO}_4\text{(s)}\).

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123630/*