Molar Absorptivity Constant Calculator

Divide the absorbance (A) by the product of the concentration (c) and path length (l) to calculate the molar absorptivity constant (ε).

The Molar Absorptivity Constant Calculator simplifies the application of Beer-Lambert Law, which relates the absorbance of a solution to its concentration, path length, and molar absorptivity. The molar absorptivity constant ( $ε$ ) quantifies how strongly a substance absorbs light at a specific wavelength. This is particularly useful in chemistry and biochemistry for determining the concentration of solutions using spectrophotometry.

Formula:

Contents

1 Formula:
2 Variables:
3 Solved Calculations:

ε = A / (c ∗ l)

Variables:

Variable	Description	Unit
ε	Molar absorptivity constant	L/(mol·cm)
A	Absorbance	Unitless
c	Concentration of the solution	mol/L
l	Path length of the cuvette	cm

Solved Calculations:

Example 1: Calculate $ε$ for a Solution with $A = 0.5$ , $c = 0.01 \, \text{mol/L}$ , $l = 1 \, \text{cm}$

READ ALSO : 100 Minute Clock Calculator

Step	Value	Explanation
Absorbance ( $A$ )	0.5	Measured absorbance
Concentration ( $c$ )	0.01 mol/L	Known concentration of the solution
Path length ( $l$ )	1 cm	Length of the light path through the solution
Formula	$ε = A / (c ∗ l)$	Substitute values into the formula
Calculation	$ε = 0.5 / (0.01 ∗ 1)$ = 50	Divide absorbance by product of $c$ and $l$
Result	50 L/(mol·cm)	Molar absorptivity constant

Example 2: Calculate $ε$ for $A = 0.8$ , $c = 0.02 \, \text{mol/L}$ , $l = 2 \, \text{cm}$

Step	Value	Explanation
Absorbance ( $A$ )	0.8	Measured absorbance
Concentration ( $c$ )	0.02 mol/L	Known concentration of the solution
Path length ( $l$ )	2 cm	Length of the light path through the solution
Formula	$ε = A / (c ∗ l)$	Substitute values into the formula
Calculation	$ε = 0.8 / (0.02 ∗ 2)$ = 20	Divide absorbance by product of $c$ and $l$
Result	20 L/(mol·cm)	Molar absorptivity constant

What is the Molar Absorptivity Constant Calculator?

The Molar Absorptivity Constant Calculator is a specialized tool. You can use it for determining the molar absorptivity (ε), a crucial parameter in Beer-Lambert’s law. It quantifies how strongly a substance absorbs light at a specific wavelength, enabling scientists to analyze concentrations in solutions based on light absorbance measurements.