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 essential in spectroscopy for determining concentrations of solutions and analyzing molecular properties.

2. How Does the Calculator Work?

The calculator uses the Beer-Lambert law formula:

Where:

• \( ε \) — Molar extinction coefficient (m²/mol)
• \( I_i \) — Intensity of incident radiation (W/m²·sr)
• \( I_t \) — Intensity of transmitted radiation (W/m²·sr)
• \( l \) — Thickness of cell (m)
• \( c \) — Concentration of solution (mol/m³)

Explanation: The log of the intensity ratio divided by the product of path length and concentration gives the extinction coefficient.

3. Importance of Molar Extinction Coefficient

Details: This value is crucial for quantitative analysis in chemistry, biochemistry, and environmental science, particularly in spectrophotometry.

4. Using the Calculator

Tips: Enter all radiation intensities, cell thickness, and solution concentration. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What are typical units for molar extinction coefficient?
A: The SI unit is m²/mol, but cm²/mol is also commonly used (1 m²/mol = 1000 cm²/mol).

Q2: How does wavelength affect the extinction coefficient?
A: The coefficient is wavelength-dependent, with maximum values typically at the absorption peak.

Q3: What's a typical range for extinction coefficients?
A: Small molecules: 10-100 m²/mol; Dyes: 1,000-10,000 m²/mol; Some proteins: up to 100,000 m²/mol.

Q4: Why use log base 10 in the formula?
A: By convention in spectroscopy, absorbance is defined using base-10 logarithms (decadic absorbance).

Q5: How accurate is this calculation?
A: Accuracy depends on precise measurement of all input parameters, especially the radiation intensities.