Table of contents

1. Chemical Measurements1h 50m
2. Tools of the Trade1h 17m
3. Experimental Error1h 52m
4 & 5. Statistics, Quality Assurance and Calibration Methods1h 57m
6. Chemical Equilibrium3h 41m
7. Activity and the Systematic Treatment of Equilibrium1h 0m
8. Monoprotic Acid-Base Equilibria1h 53m
9. Polyprotic Acid-Base Equilibria2h 17m
10. Acid-Base Titrations2h 37m
11. EDTA Titrations1h 34m
12. Advanced Topics in Equilibrium1h 16m
13. Fundamentals of Electrochemistry2h 19m
14. Electrodes and Potentiometry41m
15. Redox Titrations1h 14m
16. Electroanalytical Techniques57m
17. Fundamentals of Spectrophotometry50m

17. Fundamentals of Spectrophotometry

Measuring Absorbance

Analytical Chemistry

17. Fundamentals of Spectrophotometry

Measuring Absorbance

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Multiple Choice

Why is a specific wavelength of light chosen when recording absorbance measurements for a dye?

To minimize the amount of light absorbed by the solvent

To avoid interference from the cuvette material

To ensure the instrument uses the lowest possible energy light

To maximize sensitivity by measuring at the dye's absorbance maximum (λmax)

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Verified step by step guidance

Understand the concept of absorbance measurements: Absorbance is a measure of how much light a substance absorbs at a specific wavelength. It is governed by the Beer-Lambert law, which relates absorbance to the concentration of the absorbing species and the path length of the light through the sample.

Identify the importance of λmax: λmax is the wavelength at which a substance exhibits its maximum absorbance. This is the point where the dye absorbs the most light, making it the most sensitive wavelength for detecting changes in concentration.

Explain why λmax is chosen: By measuring absorbance at λmax, the sensitivity of the analysis is maximized. This ensures that even small changes in the dye's concentration result in noticeable changes in absorbance, improving the accuracy and reliability of the measurement.

Address the incorrect options: The other choices (minimizing light absorbed by the solvent, avoiding interference from the cuvette material, and using the lowest energy light) are not the primary reasons for selecting a specific wavelength. While these factors may be considered, they do not directly relate to maximizing sensitivity.

Conclude the reasoning: The correct answer is to maximize sensitivity by measuring at the dye's absorbance maximum (λmax), as this ensures the most accurate and sensitive detection of the dye's concentration.