Beer's Law uses which property of light to determine concentration?

Beer's Law uses which property of light to determine concentration?

• A. Transmittance
• B. Absorbance
• C. Reflectance
• D. Refractive index

Answer: (B)

Absorbance is the property Beer's Law uses to determine concentration. In Beer's Law, absorbance (A) relates directly to concentration (c) through A = εbc, where ε is molar absorptivity and b is the path length. This means, at a fixed wavelength, more solute leads to more light absorbed and thus a higher absorbance. Absorbance is defined as A = -log10(T), with T being the fraction of light that passes through. So by measuring how much light is absorbed, you can infer how concentrated the solution is. Transmittance just tells you how much light gets through, but not the amount absorbed; reflectance and refractive index describe surface reflections and light speed in the medium, not the absorption related to concentration.

Absorbance is the property Beer's Law uses to determine concentration. In Beer's Law, absorbance (A) relates directly to concentration (c) through A = εbc, where ε is molar absorptivity and b is the path length. This means, at a fixed wavelength, more solute leads to more light absorbed and thus a higher absorbance. Absorbance is defined as A = -log10(T), with T being the fraction of light that passes through. So by measuring how much light is absorbed, you can infer how concentrated the solution is. Transmittance just tells you how much light gets through, but not the amount absorbed; reflectance and refractive index describe surface reflections and light speed in the medium, not the absorption related to concentration.