---
title: "A student determines the concentration of a light-absorbing pigment using standard solutions and a spectrophotometer. Each solution is measured in a cuvette with a path length of \\(2.00\\ \\text{cm}\\). The calibration data are shown below.  | Standard concentration, \\(c\\) (\\(\\text{mol/L}\\)) | Absorbance, \\(A\\) | |—|—| | \\(0\\) | \\(0.100\\) | | \\(5.00 \\times 10^{-5}\\) | \\(0.300\\) | | \\(1.00 \\times 10^{-4}\\) | \\(0.500\\) | | \\(1.50 \\times 10^{-4}\\) | \\(0.700\\) |  The calibration line follows the relationship \\[ A=\\epsilon bc+A_0 \\] where \\(A_0\\) is the absorbance of the blank. An unknown pigment solution measured under the same conditions has an absorbance of \\(0.600\\). Which ordered pair \\(\\left(c_{\\text{unknown}},\\epsilon\\right)\\) is consistent with the data?"
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url: "https://nerd-notes.com/ubq/120027/"
date_modified: "2026-08-21T08:40:34+00:00"
---

# A student determines the concentration of a light-absorbing pigment using standard solutions and a spectrophotometer. Each solution is measured in a cuvette with a path length of \(2.00\ \text{cm}\). The calibration data are shown below.

| Standard concentration, \(c\) (\(\text{mol/L}\)) | Absorbance, \(A\) |
|—|—|
| \(0\) | \(0.100\) |
| \(5.00 \times 10^{-5}\) | \(0.300\) |
| \(1.00 \times 10^{-4}\) | \(0.500\) |
| \(1.50 \times 10^{-4}\) | \(0.700\) |

The calibration line follows the relationship
\[
A=\epsilon bc+A_0
\]
where \(A_0\) is the absorbance of the blank. An unknown pigment solution measured under the same conditions has an absorbance of \(0.600\). Which ordered pair \(\left(c_{\text{unknown}},\epsilon\right)\) is consistent with the data?

A student determines the concentration of a light-absorbing pigment using standard solutions and a spectrophotometer. Each solution is measured in a cuvette with a path length of \(2.00\ \text{cm}\). The calibration data are shown below.

| Standard concentration, \(c\) (\(\text{mol/L}\)) | Absorbance, \(A\) |
|---|---|
| \(0\) | \(0.100\) |
| \(5.00 \times 10^{-5}\) | \(0.300\) |
| \(1.00 \times 10^{-4}\) | \(0.500\) |
| \(1.50 \times 10^{-4}\) | \(0.700\) |

The calibration line follows the relationship
\[
A=\epsilon bc+A_0
\]
where \(A_0\) is the absorbance of the blank. An unknown pigment solution measured under the same conditions has an absorbance of \(0.600\). Which ordered pair \(\left(c_{\text{unknown}},\epsilon\right)\) is consistent with the data?

- **A.** \(\left(1.25 \times 10^{-5}\ \text{mol/L},\ 2.00 \times 10^3\ \text{L mol}^{-1}\text{cm}^{-1}\right)\)
- **B.** \(\left(6.25 \times 10^{-5}\ \text{mol/L},\ 4.00 \times 10^3\ \text{L mol}^{-1}\text{cm}^{-1}\right)\)
- **C.** \(\left(1.25 \times 10^{-4}\ \text{mol/L},\ 2.00 \times 10^3\ \text{L mol}^{-1}\text{cm}^{-1}\right)\)
- **D.** \(\left(1.50 \times 10^{-4}\ \text{mol/L},\ 2.00 \times 10^3\ \text{L mol}^{-1}\text{cm}^{-1}\right)\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/120027/*