To determine unknown concentrations using a standard curve, what is the relationship between absorbance and concentration?

The correct answer illustrates a fundamental principle in analytical chemistry known as Beer-Lambert law, which states that the absorbance of a solution at a given wavelength is directly proportional to the concentration of the absorbing species in the solution. This means that as the concentration of a substance increases, the absorbance measured also increases in a linear fashion, assuming constant path length and wavelength.

When you create a standard curve, you plot known concentrations against their corresponding absorbance values. The resulting linear relationship allows for the determination of unknown concentrations by measuring their absorbance and referring back to the standard curve. This direct proportionality is crucial for accurate quantification in various laboratory settings, particularly in biomedicine where precise measurements can impact diagnosis and treatment.