---
title: "A student previously prepared a calibration line for a dissolved dye using clear standards, a clean solvent blank, and clean cuvettes with a path length of \\(1.00\\text{ cm}\\). The resulting calibration relationship is \\(A=kc\\), where \\(k=\\varepsilon(1.00\\text{ cm})\\). The student retains this calibration line and calculates each unknown concentration using \\(c_{\\text{calc}}=A_{\\text{meas}}/k\\). The measured absorbance after blanking is described by  \\[ A_{\\text{meas}}=-\\log\\left(\\dfrac{I}{I_0}\\right) \\]  where \\(I\\) is the intensity transmitted through the unknown and \\(I_0\\) is the intensity transmitted through the blank. Any suspended particles considered are nonabsorbing at the selected wavelength. Which modification would cause \\(c_{\\text{calc}}\\) to be systematically greater than the actual dye concentration for the reason given?"
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url: "https://nerd-notes.com/ubq/120085/"
date_modified: "2026-08-21T08:41:23+00:00"
---

# A student previously prepared a calibration line for a dissolved dye using clear standards, a clean solvent blank, and clean cuvettes with a path length of \(1.00\text{ cm}\). The resulting calibration relationship is \(A=kc\), where \(k=\varepsilon(1.00\text{ cm})\). The student retains this calibration line and calculates each unknown concentration using \(c_{\text{calc}}=A_{\text{meas}}/k\). The measured absorbance after blanking is described by

\[
A_{\text{meas}}=-\log\left(\dfrac{I}{I_0}\right)
\]

where \(I\) is the intensity transmitted through the unknown and \(I_0\) is the intensity transmitted through the blank. Any suspended particles considered are nonabsorbing at the selected wavelength. Which modification would cause \(c_{\text{calc}}\) to be systematically greater than the actual dye concentration for the reason given?

A student previously prepared a calibration line for a dissolved dye using clear standards, a clean solvent blank, and clean cuvettes with a path length of \(1.00\text{ cm}\). The resulting calibration relationship is \(A=kc\), where \(k=\varepsilon(1.00\text{ cm})\). The student retains this calibration line and calculates each unknown concentration using \(c_{\text{calc}}=A_{\text{meas}}/k\). The measured absorbance after blanking is described by

\[
A_{\text{meas}}=-\log\left(\dfrac{I}{I_0}\right)
\]

where \(I\) is the intensity transmitted through the unknown and \(I_0\) is the intensity transmitted through the blank. Any suspended particles considered are nonabsorbing at the selected wavelength. Which modification would cause \(c_{\text{calc}}\) to be systematically greater than the actual dye concentration for the reason given?

- **A.** A fingerprint is deposited on a transparent face of each unknown cuvette after the instrument is blanked with a clean cuvette; \(c_{\text{calc}}\) is too large because the fingerprint decreases \(I\) without decreasing \(I_0\), thereby increasing \(A_{\text{meas}}\).
- **B.** The instrument is blanked with a fingerprint on the blank cuvette, and the fingerprint is removed before the unknown is measured; \(c_{\text{calc}}\) is too large because the fingerprint decreases \(I_0\).
- **C.** The blank and the unknown contain identical concentrations and size distributions of suspended particles; \(c_{\text{calc}}\) is too large because the particles scatter light away from the detector.
- **D.** The unknown and its blank are measured in clean cuvettes with a path length of \(0.80\text{ cm}\); \(c_{\text{calc}}\) is too large because the retained \(1.00\text{ cm}\) calibration slope is too large for the unknown.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/120085/*