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Beer Lambert Law

The Beer-Lambert Law describes the relationship between light absorption and the properties of the material which the light is travelling through. It relates light absorption to sample length and concentration of the sample in solution. It is commonly written as:

A = E*b*c

where,
A is the absorbance
E is the molar absorptivity, which is wavelength-dependent
b is the sample path length
c is the concentration of the sample in solution

For example, if the Absorption is 0.50, E is 1000, and the sample path length is 1 centimeter then:

0.50 = 1000*1*c

Calculating c:

C = 0.50/1000 = 0.0005 M = 5x10^-4 M

By measuring absorption, and knowing the intrinsic values of the system, such as molar absorptivity and sample path length, Beer-Lambert’s Law allows for the calculation of the concentration, which in the above example is 5x10^-4 M. Thus, understanding Beer-Lambert’s Law is fundamental for understanding the linear relationship between light absorption and the chemical properties of a particular material.

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