In the Beer-Lambert law, what unit is path length l measured in?

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Multiple Choice

In the Beer-Lambert law, what unit is path length l measured in?

Explanation:
In Beer-Lambert law, the path length is a distance traveled by light through the sample. The equation A = ε l c uses ε in units of L mol−1 cm−1, c in mol L−1, and l in cm, so that the product ε l c is unitless and A is a pure number. Because the common tabulated values of ε assume a centimeter-scale path, and standard cuvettes have a 1 cm path, l is expressed in centimeters. Using meters would require adjusting ε to keep the units consistent, but the conventional practice is to use centimeters. Therefore, the path length is measured in centimeters.

In Beer-Lambert law, the path length is a distance traveled by light through the sample. The equation A = ε l c uses ε in units of L mol−1 cm−1, c in mol L−1, and l in cm, so that the product ε l c is unitless and A is a pure number. Because the common tabulated values of ε assume a centimeter-scale path, and standard cuvettes have a 1 cm path, l is expressed in centimeters. Using meters would require adjusting ε to keep the units consistent, but the conventional practice is to use centimeters. Therefore, the path length is measured in centimeters.

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