What is the equation for Beer's law?

The equation for Beer's law, commonly described as the relationship between the absorbance (A) of light by a solution and the properties of that solution, is given by the formula:

A = εbc

In this equation:

• A represents absorbance,
• ε (epsilon) is the molar absorptivity or absorptivity coefficient,
• b is the path length of the sample cell,
• c is the concentration of the absorbing species.

Your answer of C, which is presented as A = a x b x c, aligns with the essential components of Beer's law, when "a" is interpreted as the molar absorptivity (often denoted by ε), "b" as the path length, and "c" as the concentration. This formulation captures the essence of how absorbance is directly proportional to both the concentration of the absorbing substance and the path length through which the light travels.

The other options do not accurately represent the relationship outlined by Beer's law and either misstate or misrepresent the variables involved in the concentration, path length, or absorptivity. Beer's law is a foundational principle in spectrophotometry and hence correctly understanding this equation is crucial for analyzing how light interacts with solutions.