Question

A solution of substance A with an unknown concentration was found to have an absorbance of 0.325. What is the concentration of Substance A in the solution?

a) 0.325 M
b) It cannot be determined with the given information.
c) 3.25 M
d) Depends on the volume of the solution.

Answer 1

The concentration of Substance A cannot be determined solely from the given absorbance value without the molar absorptivity or the path length information, according to Beer's Law.

Step-by-step explanation:

The question concerns how to determine the concentration of a substance based on its absorbance value in a solution. The absorbance reading of 0.325 for substance A alone cannot be used to deduce its concentration without additional information. One would need the molar absorptivity (extinction coefficient, ε) and the pathlength of the cuvette used in the spectrophotometric analysis. This relationship is described by Beer's Law, A = εbc, where A is absorbance, ε is the molar absorptivity, b is the pathlength, and c is the concentration. Without the value of ε or the pathlength (typically 1 cm), the concentration cannot be calculated. Therefore, the correct answer is that the concentration of Substance A cannot be determined with the given information.