Chapter 11, Problem 11.1DQ

Interpretation Introduction

Interpretation:

The form of the Beer-Lambert law has to be justified and the deviations from it has to be observed.

Concept introduction:

• According to Beer–Lambert law, intensity of radiation absorbed at a particular frequency depends on number of species absorbed (N), molar concentration [J] and the path length, L.

  $\begin{array}{l}{\text{I = I}}_{\text{0}}{10}^{-\epsilon \left[J\right]L}\\ \\ where,\\ \epsilon \text{ = }Molarabsorptioncoefficient\\ \text{I = }Intensityofincidentradiation\\ {\text{I}}_0\text{ = }Intensityoftransmittedradiation\end{array}$

• Equation for transmittance, T can be given as,

  $\begin{array}{c}\text{ T= }\frac{\text{I}}{{\text{I}}_{\text{0}}}\\ \\ T\text{ = }{10}^{-\epsilon \left[J\right]L}\\ \\ where,\\ \text{I = }Intensityofincidentradiation\\ {\text{I}}_0\text{ = }Intensityoftransmittedradiation\\ \text{N = }Numberofspeciesabsorbed\\ \left[J\right]\text{ = }Molarconcentration\\ L\text{ = }Pathlength\end{array}$

• Equation for absorbance, A can be given as,

  $\begin{array}{c}\text{A = }-\log \text{ T}\\ \\ T\text{ = }\epsilon \left[J\right]L\\ \\ where,\\ \text{I = }Intensityofincidentradiation\\ {\text{I}}_0\text{ = }Intensityoftransmittedradiation\\ \text{N = }Numberofspeciesabsorbed\\ \left[J\right]\text{ = }Molarconcentration\\ L\text{ = }Pathlength\end{array}$