Absorbance is a quantity used to measure chemical changes in chemistry. This quantity changes as a reaction progresses due to the differences in absorbancy between the reactants and products of a reaction. The change in absorbance, sometimes called optical density, is calculated from spectroscopy data collected during an experimental reaction. The absorbancy is not to be mistaken with transmittance, which is the measure of how much light, in a specific wavelength, penetrates through a material.
Take the base ten logarithm of the the initial light intensity.
Take the base ten logarithm of the the final light intensity.
Subtract the resulting logarithmic value of intensity of the final from the initial. The resulting value is the absorbancy of the material.
Determining Absorbance Change
Determine the absorbance at the initial and ending portions of the process being examined.
Divide the final absorbance by the initial.
Multiply the resulting value by 100 to determine the change, as a percentage, in absorbance.
- "Chemistry, 5th edition"; John E. McMurry, Robert C. Fay; 2008
- Michigan State University: Visible and Ultraviolet Spectroscopy; William Reusch; 1999
- New Mexico Climate Center: Atomic Absorption Spectroscopy; Elena Sevostianova; n.d.
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