In absorption spectrophotometry, which statement is true?

In absorption spectrophotometry, absorbance is a crucial measurement that reflects how much light is absorbed by a sample. According to Beer-Lambert law, absorbance is directly proportional to the concentration of the absorbing species in the solution, as well as the path length of the light through the sample. This relationship allows for the quantification of concentrations of substances based on how much light they absorb at a specific wavelength.

When light of a certain wavelength passes through a solution, some light is absorbed while the rest is transmitted. The absorbance value provides a measure of the amount of light that has been absorbed, and it can be calculated from the transmittance values. However, it is important to understand that absorbance increases with concentration; thus, as the concentration of the absorbing species increases, so does the absorbance. This makes the relationship between absorbance and concentration fundamental for analytical techniques used to determine the concentration of unknown samples.

The other options discuss relationships involving transmittance and path length, which do not directly define the relationship between absorbance and concentration. Therefore, the statement regarding absorbance being proportional to concentration accurately captures an essential aspect of absorption spectrophotometry.