A substance, X, has a molar absorptivity of 1250 L mol^-1 cm^-1 at 325 nm. A sample of X gives an absorbance of 0.8 when measured in a UV-visible spectrophotometer at 325 nm with a path length of 1 cm. What is the concentration of the sample of X? A) 1000 mol L^-1 B) 1 mol L^-1 C) 1563 mol L^-1 D) 6.4*10^-4 mol L^-1 E) 1.56 mol L^-1

Question

Quizplus · Accepted Answer

The absorbance of a sample is given by the Beer-Lambert law:A = εbcwhere A is the absorbance, ε is the molar absorptivity, b is the path length, and c is the concentration.In this problem, we are given the following information:ε = 1250 L mol^-1 cm^-1A = 0.8b = 1 cmWe can use the Beer-Lambert law to solve for the concentration:c = A/εb = 0.8/(1250 L mol^-1 cm^-1 * 1 cm) = 6.4 x 10^-4 mol L^-1Therefore, the concentration of the sample of X is 6.4 x 10^-4 mol L^-1.

A Substance, X, Has a Molar Absorptivity of 1250 L