Chapter 18, Problem 18.19P

Interpretation Introduction

Interpretation:

Value of molar absorptivity at a wavelength of $\text{438 nm}$ that has an absorbance of 0.728 has to be calculated.

Concept Introduction:

Molar absorptivity is a coefficient that appears in Beers’ law. It measures the extent of light absorbed at a certain wavelength. Molar absorptivity is denoted by the symbol $\epsilon$. SI unit for Molar absorptivity is ${\text{M}}^{-1}{\text{cm}}^{-1}$.

Expression to compute absorbance as per Beer’s law is as follows:

  $A=\epsilon \cdot b\cdot c$

Here,

$\epsilon$ denotes molar absorptivity of species capable to absorb in ${\text{M}}^{-1}{\text{cm}}^{-1}$.

$b$ denotes path length in centimeters.

$c$ denotes concentration or molarity of species capable to absorb.

$A$ denotes absorbance.

$T$ denotes transmittance.