AP Chemistry Flashcards: Beer-Lambert Law
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 10 cards to help you master important concepts.
What three factors determine the amount of light absorbed by a solution?
The amount of light absorbed is determined by the solution's concentration, the path length the light travels, and the molar absorptivity of the species.
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What three factors determine the amount of light absorbed by a solution?
The amount of light absorbed is determined by the solution's concentration, the path length the light travels, and the molar absorptivity of the species.
In an experiment, which two factors are typically held constant to establish a direct relationship between absorbance and concentration?
The path length (by using the same sample container) and the wavelength of light are typically held constant.
Identify the variables in the Beer-Lambert Law equation: A = εbc.
A is absorbance, ε is molar absorptivity, b is the path length, and c is the concentration of the solution.
In a typical Beer-Lambert Law experiment, why is the wavelength of maximum absorbance used?
Measurements are made at the wavelength of maximum absorbance to achieve the highest sensitivity for the analysis.
If you double the concentration of a solution while keeping other factors constant, what will happen to its absorbance?
According to the Beer-Lambert law, since absorbance is directly proportional to concentration, doubling the concentration will also double the absorbance.
What does 'ε' (epsilon) represent in the Beer-Lambert Law (A = εbc)?
The variable 'ε' represents molar absorptivity, a constant that indicates how strongly a species absorbs light at a specific wavelength.
How does the Beer-Lambert Law simplify when conducting an experiment where the same substance and cuvette are used for all measurements?
In this scenario, molar absorptivity (ε) and path length (b) are held constant, making absorbance (A) directly proportional only to concentration (c).
What does 'b' represent in the Beer-Lambert Law (A = εbc)?
The variable 'b' represents the path length, which is the distance the light travels through the solution, typically held constant in experiments.
What is the relationship between absorbance and concentration when path length and molar absorptivity are held constant?
When path length and molar absorptivity are constant, absorbance is directly proportional to the concentration of the absorbing species.
What is the Beer-Lambert Law?
The Beer-Lambert law is an equation (A = εbc) that relates a solution's light absorption (A) to its molar absorptivity (ε), path length (b), and concentration (c).