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

Which of the following best describes the relationship between the concentration of allura red dye solutions and their absorbance, according to Beer-Lambert Law?

Absorbance increases linearly with increasing concentration.

Absorbance decreases as concentration increases.

Absorbance is unrelated to concentration.

Absorbance remains constant regardless of concentration.

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Verified step by step guidance

Understand the Beer-Lambert Law, which states that absorbance (A) is directly proportional to the concentration (c) of the absorbing species in solution. The mathematical expression is:

A = ε c l

, where

ε

is the molar absorptivity and

l

is the path length.

Recognize that the relationship described by Beer-Lambert Law is linear, meaning that as the concentration of the dye increases, the absorbance will increase proportionally, assuming the system adheres to the law.

Consider the options provided in the problem. The correct description of the relationship is that absorbance increases linearly with increasing concentration, as per the Beer-Lambert Law.

Eliminate incorrect options: Absorbance does not decrease with increasing concentration, nor is it unrelated or constant regardless of concentration. These statements contradict the Beer-Lambert Law.

Conclude that the correct answer is: 'Absorbance increases linearly with increasing concentration,' as this aligns with the principles of the Beer-Lambert Law.