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Absorbance Formula:
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Absorbance (A) is a measure of the amount of light absorbed by a sample. It is a dimensionless quantity used in spectroscopy to quantify how much light is absorbed by a substance at a particular wavelength.
The calculator uses the absorbance formula:
Where:
Explanation: The formula calculates absorbance from transmittance using the base-10 logarithm. As transmittance decreases (less light passes through), absorbance increases.
Details: Absorbance measurements are fundamental in analytical chemistry, particularly in spectrophotometry. They are used to determine concentrations of substances in solution using Beer-Lambert law, study reaction kinetics, and analyze chemical properties.
Tips: Enter transmittance as a decimal value between 0 and 1. For example, 50% transmittance should be entered as 0.5. The calculator will compute the corresponding absorbance value.
Q1: What is the relationship between absorbance and transmittance?
A: Absorbance and transmittance have an inverse logarithmic relationship. As transmittance decreases, absorbance increases exponentially.
Q2: What are typical absorbance values?
A: Absorbance values typically range from 0 to 2 for accurate measurements. Values above 2 may indicate too much absorption for reliable quantification.
Q3: How is absorbance related to concentration?
A: According to Beer-Lambert law, absorbance is directly proportional to concentration: A = εlc, where ε is molar absorptivity, l is path length, and c is concentration.
Q4: Why use logarithmic scale for absorbance?
A: The logarithmic scale compresses the wide range of light absorption values into a more manageable linear scale that is proportional to concentration.
Q5: What instruments measure absorbance?
A: Spectrophotometers and colorimeters are commonly used to measure absorbance at specific wavelengths of light.