---
title: "A student prepares five standard solutions of \\(\\text{CuSO}_4\\text{(aq)}\\) with known concentrations and measures the absorbance of each solution at a wavelength of \\(635\\text{ nm}\\) using a spectrophotometer with a path length of \\(1.00\\text{ cm}\\). The resulting calibration curve is shown below.  If the absorbance of a \\(\\text{CuSO}_4\\text{(aq)}\\) sample of unknown concentration is \\(0.30\\) when measured under identical conditions, what is the concentration of \\(\\text{Cu}^{2+}\\) in the sample?"
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date_modified: "2026-08-21T08:12:08+00:00"
---

# A student prepares five standard solutions of \(\text{CuSO}_4\text{(aq)}\) with known concentrations and measures the absorbance of each solution at a wavelength of \(635\text{ nm}\) using a spectrophotometer with a path length of \(1.00\text{ cm}\). The resulting calibration curve is shown below.

If the absorbance of a \(\text{CuSO}_4\text{(aq)}\) sample of unknown concentration is \(0.30\) when measured under identical conditions, what is the concentration of \(\text{Cu}^{2+}\) in the sample?

A student prepares five standard solutions of \(\text{CuSO}_4\text{(aq)}\) with known concentrations and measures the absorbance of each solution at a wavelength of \(635\text{ nm}\) using a spectrophotometer with a path length of \(1.00\text{ cm}\). The resulting calibration curve is shown below.

If the absorbance of a \(\text{CuSO}_4\text{(aq)}\) sample of unknown concentration is \(0.30\) when measured under identical conditions, what is the concentration of \(\text{Cu}^{2+}\) in the sample?

![A grayscale Cartesian graph showing a calibration curve. The horizontal axis is labeled Concentration of \(\text{Cu}^{2+}\text{ (M)}\) with labeled tick marks at \(0.00\), \(0.02\), \(0.04\), \(0.06\), \(0.08\), and \(0.10\). The vertical axis is labeled Absorbance with labeled tick marks at \(0.00\), \(0.20\), \(0.40\), \(0.60\), \(0.80\), and \(1.00\). A fine gray grid displays horizontal gridlines spaced every \(0.10\) units on the vertical axis and vertical gridlines spaced every \(0.01\text{ M}\) on the horizontal axis. A single solid black best-fit line begins at the origin \((0.00, 0.00)\) and passes continuously through five solid black circular data points at \((0.02, 0.20)\), \((0.04, 0.40)\), \((0.06, 0.60)\), \((0.08, 0.80)\), and \((0.10, 1.00)\). No other particles, labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1787299928-RZCNAb.jpg)

- **A.** \(0.030\text{ M}\)
- **B.** \(0.060\text{ M}\)
- **C.** \(0.30\text{ M}\)
- **D.** \(0.60\text{ M}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119720/*