Molar Absorptivity Constant Calculator

This calculator can be used to determine the molar absorptivity constant (ε) using Beer-Lambert Law, which relates absorbance of a substance to its concentration and path length.

Input Parameters

Calculation Results

Calculation Formula

ε = A / (c × l)

Where:
ε = Molar absorptivity constant (L mol⁻¹ cm⁻¹)
A = Absorbance
c = Concentration (mol/L)
l = Path length (cm)

Result

Molar Absorptivity Constant Calculator Usage Guide

Learn how to use the Molar Absorptivity Constant Calculator and its working principles

How to Use the Calculator

  1. Enter the absorbance (A) of your solution.
  2. Enter the concentration (c) of your solution in mol/L.
  3. Enter the path length (l) of your solution in cm (typically 1 cm for cuvettes).
  4. Click the "Calculate" button to compute the molar absorptivity constant (ε).
  5. The result will be displayed in L mol⁻¹ cm⁻¹.

Beer-Lambert Law

The Beer-Lambert Law relates the absorbance of a solution to its concentration and path length. The formula is:

A = ε × c × l

Where:

  • A = Absorbance (unitless)
  • ε = Molar absorptivity constant (L mol⁻¹ cm⁻¹)
  • c = Concentration (mol/L)
  • l = Path length (cm)

Practical Applications

The molar absorptivity constant is an important parameter in spectroscopy, particularly in UV-Vis spectroscopy. It helps in determining the concentration of a substance in a solution by measuring its absorbance.

Example Calculation

For example, if a solution has an absorbance of 0.5, a concentration of 0.01 mol/L, and a path length of 1 cm, the molar absorptivity constant would be:

ε = 0.5 / (0.01 × 1) = 50 L mol⁻¹ cm⁻¹