Home
Back
Molar Extinction Coefficient Formula:
| From: | To: |
The molar extinction coefficient (ε) is a measure of how strongly a chemical species absorbs light at a particular wavelength. It is a fundamental parameter in spectroscopy and is used to quantify the concentration of substances in solution using the Beer-Lambert law.
The calculator uses the Beer-Lambert law formula:
Where:
Explanation: The molar extinction coefficient represents the absorbance of a 1 molar solution in a 1 cm path length cuvette at a specific wavelength.
Details: The molar extinction coefficient is crucial for determining unknown concentrations in spectrophotometric analysis, characterizing chemical compounds, and understanding light-matter interactions in various scientific fields including chemistry, biochemistry, and environmental science.
Tips: Enter absorbance (unitless), concentration in mol/L, and path length in cm. All values must be positive numbers. Ensure measurements are taken at the same wavelength for accurate results.
Q1: What is a typical range for molar extinction coefficients?
A: Values range from near zero for non-absorbing compounds to over 100,000 L/mol·cm for strongly absorbing dyes and pigments.
Q2: Does the extinction coefficient depend on wavelength?
A: Yes, the molar extinction coefficient is wavelength-dependent and is typically reported at the wavelength of maximum absorption (λmax).
Q3: How is this different from absorption coefficient?
A: Molar extinction coefficient is per mole concentration, while absorption coefficient may refer to mass concentration or other units.
Q4: What factors affect the extinction coefficient?
A: Solvent, temperature, pH, and molecular structure all influence the extinction coefficient value.
Q5: Can this calculator be used for any wavelength?
A: Yes, but remember that the extinction coefficient is wavelength-specific, so ensure all measurements are at the same wavelength.