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

• A. Absorbance increases linearly with increasing concentration.
• B. Absorbance decreases as concentration increases.
• C. Absorbance is unrelated to concentration.
• D. Absorbance remains constant regardless of concentration.

Answer: (A)

Verified step by step guidance

1. 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: $A=\epsilon cl$, where $\epsilon$ is the molar absorptivity and $l$ is the path length.
2. 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.
3. 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.
4. 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.
5. Conclude that the correct answer is: 'Absorbance increases linearly with increasing concentration,' as this aligns with the principles of the Beer-Lambert Law.