The Extension Coefficient Calculator is a scientific tool used to determine how strongly a chemical substance absorbs light at a particular wavelength. This value, known as the extension coefficient (or molar absorptivity), is a fundamental concept in spectrophotometry and plays a crucial role in laboratory research, biochemical assays, pharmaceutical quality control, and environmental analysis.
By inputting values for absorbance, concentration, and path length, this calculator quickly provides the extension coefficient, which tells you how effective a compound is at absorbing light. This data is essential for calculating unknown concentrations and ensuring accurate analytical measurements.
formula of Extension Coefficient Calculator
Where:
- ε = Extension Coefficient (L·mol⁻¹·cm⁻¹)
- A = Absorbance (unitless, measured using a spectrophotometer)
- c = Concentration of the solution (mol/L)
- l = Path Length of the light through the sample (cm)
This formula is based on the Beer-Lambert Law, which describes the linear relationship between absorbance and concentration for a given wavelength. A higher extension coefficient means the substance absorbs more light, even at low concentrations.
Quick Reference Table for Lab Users
| Absorbance (A) | Concentration (mol/L) | Path Length (cm) | Calculated ε (L·mol⁻¹·cm⁻¹) |
|---|---|---|---|
| 0.500 | 0.0010 | 1.0 | 500 |
| 1.200 | 0.0020 | 1.0 | 600 |
| 0.300 | 0.0005 | 1.0 | 600 |
| 0.900 | 0.0015 | 1.0 | 600 |
This table helps quickly estimate extension coefficients without needing to re-calculate common values repeatedly.
Example of Extension Coefficient Calculator
Suppose a laboratory technician measures an absorbance (A) of 0.750 for a solution. The solution’s concentration (c) is 0.0025 mol/L, and the path length (l) through the cuvette is 1 cm.
Now apply the formula:
ε = 0.750 / (0.0025 × 1)
ε = 0.750 / 0.0025 = 300 L·mol⁻¹·cm⁻¹
This result means the substance has a moderate ability to absorb light at the measured wavelength.
Most Common FAQs
This calculator is classified under chemical analysis tools and spectrophotometry calculators. It is mainly used in scientific laboratories and research institutions.
Yes, as long as the absorbance is measured at a specific wavelength using a calibrated spectrophotometer. Each substance has a unique extension coefficient at different wavelengths.
Using centimeters (typically 1 cm cuvettes) standardizes the formula and ensures consistency across labs. Always convert units before using the calculator for accurate results.