---
title: "A student performs a laboratory experiment to determine the value of \\(x\\) in the formula of hydrated copper(II) sulfate, \\(\\text{CuSO}_4 \\cdot x\\text{H}_2\\text{O}\\). A sample of the hydrate is placed in an open crucible and heated strongly to drive off all the water of hydration according to the following equation:  \\[ \\text{CuSO}_4 \\cdot x\\text{H}_2\\text{O}(s) \\rightarrow \\text{CuSO}_4(s) + x\\,\\text{H}_2\\text{O}(g) \\]  During heating, some of the solid splatters out of the crucible and is lost. If the student does not notice this loss and uses the final mass of the crucible and residue to calculate \\(x\\), how will the calculated value of \\(x\\) compare to the actual value, and why?"
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url: "https://nerd-notes.com/ubq/119617/"
date_modified: "2026-08-21T08:11:48+00:00"
---

# A student performs a laboratory experiment to determine the value of \(x\) in the formula of hydrated copper(II) sulfate, \(\text{CuSO}_4 \cdot x\text{H}_2\text{O}\). A sample of the hydrate is placed in an open crucible and heated strongly to drive off all the water of hydration according to the following equation:

\[ \text{CuSO}_4 \cdot x\text{H}_2\text{O}(s) \rightarrow \text{CuSO}_4(s) + x\,\text{H}_2\text{O}(g) \]

During heating, some of the solid splatters out of the crucible and is lost. If the student does not notice this loss and uses the final mass of the crucible and residue to calculate \(x\), how will the calculated value of \(x\) compare to the actual value, and why?

A student performs a laboratory experiment to determine the value of \(x\) in the formula of hydrated copper(II) sulfate, \(\text{CuSO}_4 \cdot x\text{H}_2\text{O}\). A sample of the hydrate is placed in an open crucible and heated strongly to drive off all the water of hydration according to the following equation:

\[ \text{CuSO}_4 \cdot x\text{H}_2\text{O}(s) \rightarrow \text{CuSO}_4(s) + x\,\text{H}_2\text{O}(g) \]

During heating, some of the solid splatters out of the crucible and is lost. If the student does not notice this loss and uses the final mass of the crucible and residue to calculate \(x\), how will the calculated value of \(x\) compare to the actual value, and why?

- **A.** Too low, because the loss of solid decreases the measured mass of the residue, which directly decreases the calculated moles of \(\text{CuSO}_4\).
- **B.** Too low, because the loss of solid reduces the total amount of water that is available to vaporize from the sample remaining in the crucible.
- **C.** Too high, because the loss of solid decreases the recorded mass of the residue, which incorrectly increases the calculated moles of \(\text{CuSO}_4\).
- **D.** Too high, because the mass of the lost solid is incorrectly attributed to evaporated water, resulting in an overestimate of the moles of \(\text{H}_2\text{O}\) and an underestimate of the moles of \(\text{CuSO}_4\).

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119617/*