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Beer-Lambert Law:
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Molar absorptivity (ε), also known as the molar extinction coefficient, is a measure of how strongly a chemical species absorbs light at a particular wavelength. It is a fundamental property in spectroscopy and quantitative analysis.
The calculator uses the Beer-Lambert Law:
Where:
Explanation: The Beer-Lambert Law describes the linear relationship between absorbance and concentration of an absorbing species in solution.
Details: Molar absorptivity is crucial for quantitative analysis in spectroscopy, determining unknown concentrations, characterizing compounds, and validating analytical methods in chemistry and biochemistry.
Tips: Enter absorbance (unitless), concentration in mol/L, and path length in cm. All values must be positive numbers. Standard path length for most spectrophotometers is 1.0 cm.
Q1: What are typical values for molar absorptivity?
A: Values range from near zero for non-absorbing compounds to over 100,000 L/mol·cm for strongly absorbing chromophores. Most organic compounds have values between 1,000-50,000 L/mol·cm.
Q2: Does molar absorptivity depend on wavelength?
A: Yes, molar absorptivity is wavelength-dependent and is typically reported at the wavelength of maximum absorption (λmax).
Q3: What factors affect molar absorptivity?
A: Temperature, solvent, pH, and molecular structure can all influence molar absorptivity values.
Q4: How accurate is this calculation?
A: The calculation assumes the Beer-Lambert Law holds true, which requires monochromatic light, dilute solutions, and no chemical associations.
Q5: Can this be used for mixture analysis?
A: For mixtures, additional mathematical treatment is needed, such as using multiple wavelengths and solving simultaneous equations.