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Beer-Lambert Law Equation:
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Molar absorptivity (ε), also known as molar extinction coefficient, is a measure of how strongly a chemical species absorbs light at a given wavelength. It is a fundamental property in spectrophotometry and is used to quantify the concentration of substances in solution.
The calculator uses the Beer-Lambert Law equation:
Where:
Explanation: The Beer-Lambert Law describes the relationship between the absorption of light and the properties of the material through which the light is traveling.
Details: Molar absorptivity is crucial in analytical chemistry for determining unknown concentrations, characterizing compounds, and understanding molecular structure and electronic transitions.
Tips: Enter absorbance (typically between 0.1-1.0 for accurate measurements), concentration in mol/L, and path length in cm. All values must be positive numbers.
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.
Q2: Why is molar absorptivity wavelength-dependent?
A: Different molecules absorb light at different wavelengths based on their electronic structure, making ε specific to both the compound and the wavelength used.
Q3: What affects the accuracy of molar absorptivity measurements?
A: Factors include instrument calibration, sample purity, temperature, solvent effects, and ensuring measurements are within the linear range of the instrument.
Q4: Can molar absorptivity be used for mixture analysis?
A: Yes, but it requires measurements at multiple wavelengths and solving simultaneous equations when multiple absorbing species are present.
Q5: How does path length affect the calculation?
A: Longer path lengths result in greater absorption for the same concentration, which is why standard cuvettes are typically 1 cm in length for comparability.