Molar Extinction Coefficient Formula:
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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.
The calculator uses the Beer-Lambert law formula:
Where:
Explanation: The log of the intensity ratio divided by the product of path length and concentration gives the extinction coefficient.
Details: This value is crucial for quantitative analysis in chemistry, biochemistry, and environmental science, particularly in spectrophotometry.
Tips: Enter all radiation intensities, cell thickness, and solution concentration. All values must be positive numbers.
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.