What is Absorbance?

Absorbance is a measure of how much light is absorbed by a substance. When light passes through a substance, some of the light may be absorbed by the molecules in the substance. The amount of light absorbed is related to the concentration of the absorbing substance and the path length of the light through the substance. Absorbance is commonly used in chemistry and environmental science to quantify the amount of a particular substance in a sample.

Factors Affecting Absorbance

Several factors can affect the absorbance of a substance:

Concentration: The higher the concentration of the absorbing substance, the more light will be absorbed.
Path Length: The longer the path length of light through the substance, the more light will be absorbed.
Wavelength of Light: Different substances absorb light at different wavelengths, so the wavelength of the light used will affect the absorbance.

Measuring Absorbance

Absorbance is typically measured using a spectrophotometer, which shines light of a specific wavelength through a sample and measures the amount of light that is absorbed. The absorbance of the sample is then calculated based on the amount of light absorbed.

Study Guide

Here are some key points to remember about absorbance:

Absorbance measures how much light is absorbed by a substance.
Factors affecting absorbance include concentration, path length, and the wavelength of light.
Spectrophotometers are commonly used to measure absorbance in laboratory settings.
Understanding absorbance is important in fields such as chemistry, environmental science, and biochemistry.

When studying absorbance, it's important to understand the relationship between concentration, path length, and the amount of light absorbed. Practice using spectrophotometers and interpreting absorbance data to reinforce your understanding of the concept.