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Molar Absorptivity Formula:
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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 given wavelength. It is a fundamental property in spectrophotometry and is derived from Beer-Lambert law.
The calculator uses the Beer-Lambert law formula:
Where:
Explanation: This formula calculates how much light a substance absorbs per mole per centimeter path length at a specific wavelength.
Details: Molar absorptivity is crucial in quantitative analysis, chemical identification, and determining unknown concentrations in spectrophotometric methods. It is characteristic for each substance at specific wavelengths.
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: Values typically range from 0 to over 100,000 L·mol⁻¹·cm⁻¹, with higher values indicating stronger light 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 each wavelength.
Q3: What are ideal absorbance values for accurate measurements?
A: Absorbance values between 0.1 and 1.0 provide the most accurate results, as values below 0.1 have low sensitivity and above 1.0 may deviate from Beer's law.
Q4: Can molar absorptivity be used to identify compounds?
A: Yes, the characteristic absorption spectrum and specific ε values at certain wavelengths can help identify chemical compounds.
Q5: How does temperature affect molar absorptivity?
A: Temperature generally has minimal effect on ε, but significant temperature changes can affect solvent properties and molecular interactions.