Beer-Lambert Law Calculator w/ Formula

Enter the molar absorption coefficient, concentration, and path length into the calculator to determine the total absorbance.

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Beer-Lambert Law Formula

The following equation is used to calculate the absorbance of a substance.

A = ma * c * l 

• Where A is the absorbance
• ma is the molar absorption coefficient (m*2/mol)
• c is the concentration (mol/L)
• l is the path length (m)

To calculate absorbance from the Beer-Lambert Law, multiply the molar absorption coefficient by the concentration, then multiply by the path length.

Beer-Lambert Law Definition

The Beer-Lambert Law, also known as the Beer-Lambert-Bouguer Law or simply Beer’s Law, is a fundamental principle in spectroscopy that relates the concentration of a solute in a solution to the absorption of light by that solution.

It is named after the scientists August Beer and Johann Lambert, who independently formulated the law in the mid-19th century.

The law states that the absorbance (A) of light passing through a sample is directly proportional to the concentration (c) of the absorbing species and the path length (l) that the light travels through the sample. Mathematically, this relationship is represented as A = εcl, where ε is the molar absorptivity or molar absorption coefficient, a constant unique to each absorbing species and wavelength of light.

The Beer-Lambert Law is crucial in various scientific disciplines, particularly chemistry, biochemistry, and environmental science. It provides a quantitative method to determine the concentration of a solute in a solution by measuring the absorbance of light at a specific wavelength.

This enables scientists to analyze the composition and concentration of substances, such as pollutants in water, reactants in chemical reactions, or biomolecules in biological samples.

Beer-Lambert Law Example

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