Light

Molar Absorptivity

Definition

Molar absorptivity, also known as the molar absorption coefficient, measures how much light a specific compound can absorb at a given wavelength. It's usually denoted by ε and its units are L mol⁻¹ cm⁻¹.

Analogy

Imagine going to a concert with different colored spotlights shining on the crowd. Some people are wearing clothes that glow under certain colors - these people are like molecules with high molar absorptivity for those colors. They 'absorb' or react more strongly to certain wavelengths of light.

Related terms

Absorption Spectrum: This refers to the range of wavelengths that a substance can absorb. In our concert analogy, this would represent all possible spotlight colors and which ones make someone's clothes glow.

Wavelength: The distance between two peaks in any wave-based phenomenon including light waves. In the concert analogy, this would be like the color of the spotlight.

Transmittance: The measure of how much light passes through a sample without being absorbed. If everyone at the concert wore black (which doesn't glow under any colored spotlights), they'd have high transmittance because all light colors pass through without causing a reaction.