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title: "A student uses clean cuvettes to prepare a calibration curve for an aqueous dye. The instrument is blanked with solvent, and the resulting calibration line has a positive slope and passes through the origin. For the spectrophotometer, \\(A=-\\log(T)\\), where \\(T=\\dfrac{I}{I_0}\\).  After collecting the calibration data, the student leaves fingerprint smudges on an optical face of the cuvette containing the unknown solution. The smudges are in the light-beam path, and the measured absorbance remains within the linear range of the calibration curve. Which choice correctly describes how the smudges affect the concentration calculated for the unknown?"
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url: "https://nerd-notes.com/ubq/119380/"
date_modified: "2026-08-19T12:40:04+00:00"
---

# A student uses clean cuvettes to prepare a calibration curve for an aqueous dye. The instrument is blanked with solvent, and the resulting calibration line has a positive slope and passes through the origin. For the spectrophotometer, \(A=-\log(T)\), where \(T=\dfrac{I}{I_0}\).

After collecting the calibration data, the student leaves fingerprint smudges on an optical face of the cuvette containing the unknown solution. The smudges are in the light-beam path, and the measured absorbance remains within the linear range of the calibration curve. Which choice correctly describes how the smudges affect the concentration calculated for the unknown?

A student uses clean cuvettes to prepare a calibration curve for an aqueous dye. The instrument is blanked with solvent, and the resulting calibration line has a positive slope and passes through the origin. For the spectrophotometer, \(A=-\log(T)\), where \(T=\dfrac{I}{I_0}\).

After collecting the calibration data, the student leaves fingerprint smudges on an optical face of the cuvette containing the unknown solution. The smudges are in the light-beam path, and the measured absorbance remains within the linear range of the calibration curve. Which choice correctly describes how the smudges affect the concentration calculated for the unknown?

- **A.** The calculated concentration is too low because the decreased intensity reaching the detector corresponds to a smaller absorbance.
- **B.** The calculated concentration is too low because some incident light is absorbed or scattered by the smudges rather than absorbed by the dye.
- **C.** The calculated concentration is unchanged because blanking the instrument corrects for light absorbed or scattered by the cuvette and its smudges.
- **D.** The calculated concentration is too high because the smudges decrease the transmitted intensity, increasing the measured absorbance attributed to the dye.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119380/*