1. What is Molar Extinction Coefficient?

Definition: The Molar Extinction Coefficient measures how strongly a chemical species absorbs light at a particular wavelength.

Purpose: It's used in spectroscopy to determine concentrations of solutions and characterize substances based on their light absorption properties.

2. How Does the Calculator Work?

The calculator uses the Beer-Lambert Law formula:

Where:

• \( ε \) — Molar extinction coefficient (m²/mol)
• \( A \) — Absorbance (unitless)
• \( c \) — Concentration of solution (mol/m³)
• \( l \) — Thickness of cell/path length (m)

Explanation: The absorbance is divided by the product of concentration and path length to determine how strongly the substance absorbs light.

3. Importance of Molar Extinction Coefficient

Details: This coefficient is fundamental in quantitative spectroscopy, allowing researchers to determine unknown concentrations and compare absorption properties of different substances.

4. Using the Calculator

Tips: Enter the measured absorbance, solution concentration (in mol/m³), and path length (in meters). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for molar extinction coefficients?
A: They vary widely - from less than 10 m²/mol for weak absorbers to over 100,000 m²/mol for strongly absorbing dyes.

Q2: How does wavelength affect the extinction coefficient?
A: The coefficient is wavelength-dependent, with maximum absorption typically occurring at specific wavelengths for each substance.

Q3: What units should I use for concentration?
A: This calculator uses mol/m³. For molarity (mol/L), multiply your value by 1000 (1 mol/L = 1000 mol/m³).

Q4: Why is path length important?
A: Longer path lengths result in more absorption, so the coefficient must account for this by normalizing to 1 meter.

Q5: Can I use this for mixtures?
A: The calculated value would represent an apparent coefficient for the mixture, not individual components.