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Molar Absorptivity Equation:
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Molar absorptivity (also known as extinction coefficient) is a measure of how strongly a chemical species absorbs light at a given wavelength. It is a fundamental property in spectroscopy that quantifies the absorption characteristics of a substance.
The calculator uses the Beer-Lambert law equation:
Where:
Explanation: The Beer-Lambert law describes the relationship between absorbance and the properties of the material through which light is passing. Molar absorptivity is specific to each substance and wavelength.
Details: Molar absorptivity is crucial for quantitative analysis in spectroscopy, determining unknown concentrations, characterizing substances, and in various applications including pharmaceutical analysis, environmental monitoring, and biochemical research.
Tips: Enter absorbance (typically between 0.1-1.0 for accurate measurements), concentration in mol/L, and path length in cm. Ensure all values are positive and concentration and path length are greater than zero.
Q1: What is the typical range for molar absorptivity values?
A: Molar absorptivity values typically range from 0 to over 100,000 L/mol·cm, with higher values indicating stronger absorption at that wavelength.
Q2: How does wavelength affect molar absorptivity?
A: Molar absorptivity is wavelength-dependent. Each substance has characteristic absorption peaks where molar absorptivity is maximum.
Q3: What are the limitations of the Beer-Lambert law?
A: The law assumes monochromatic light, non-scattering solutions, and no chemical associations. It may not hold at very high concentrations.
Q4: How is molar absorptivity used in concentration determination?
A: Once molar absorptivity is known for a substance at a specific wavelength, it can be used to calculate unknown concentrations using the same equation.
Q5: What factors can affect molar absorptivity measurements?
A: Temperature, solvent, pH, and the presence of other absorbing species can affect molar absorptivity values.