Beer's Law
Beer's Law is often written in the form of this equation A =
abc as a way of summarizing and quantifying the relationship between the absorbance,
the nature of the absorbing chemical, the path length of the solution,
and the concentration of the solution. It expresses the ideal situation
in which these factors are truly proportional to the absorbance.
 | The symbol "A" stands for the absorbance
which you will measure with an instrument. |
| The symbol "c" stands for concentration
measured in molarity. |
| The symbol "b" stands for the path length
measured in centimeters. |
| The symbol "a" is a proportionality factor called the molar
absorptivity which is how much light will be absorbed by 1 cm of a 1 M
solution of this chemical. Its value depends on what the chemical is and also on what
wavelength (or color) of light is being used. |
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Sue Eggling
Clackamas Community College
©1998, 2003 Clackamas Community College, Hal Bender
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