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Beer-Lambert Law:
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The molar extinction coefficient (ε) is a measure of how strongly a chemical species absorbs light at a given wavelength. It is a fundamental property 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:
Where:
Explanation: The equation relates the absorption of light to the properties of the material through which the light is traveling.
Details: The molar extinction coefficient is crucial for determining concentrations of unknown samples, characterizing chemical compounds, and is widely used in biochemistry, analytical chemistry, and pharmaceutical sciences.
Tips: Enter absorbance (typically between 0.1-1.0 for accurate measurements), concentration in molar units (M), and path length in centimeters (cm). All values must be positive and non-zero.
Q1: What is a typical range for molar extinction coefficients?
A: Values range from near zero for transparent compounds to over 100,000 M⁻¹·cm⁻¹ for strongly absorbing dyes and pigments.
Q2: Does the extinction coefficient depend on wavelength?
A: Yes, extinction coefficients are wavelength-specific and are usually reported at the wavelength of maximum absorption (λmax).
Q3: Why is the Beer-Lambert law important?
A: It provides a linear relationship between absorbance and concentration, making it fundamental for quantitative analysis in spectroscopy.
Q4: What are common sources of error in this calculation?
A: Errors can come from inaccurate concentration measurements, non-monochromatic light, stray light, chemical reactions, or deviations from ideal Beer-Lambert behavior at high concentrations.
Q5: Can this calculator be used for any wavelength?
A: Yes, but remember that the extinction coefficient is wavelength-dependent, so the calculated value applies only to the specific wavelength used for the absorbance measurement.