3.13 Beer-Lambert Law

The Beer-Lambert Law, also called Beer’s Law, describes how much light a solution absorbs. It depends on three main factors: the path length that the light travels through the solution, the molar absorptivity of the substance, and the concentration of the solution. These are related by the equation where A is absorbance, ${\varepsilon}$ is molar absorptivity, b is path length, and c is concentration. If the path length increases, the light passes through more solution and more can be absorbed. If concentration increases, there are more absorbing particles present, so absorbance increases as well.