Chapter 11, Problem 11.KE

(a)

Interpretation Introduction

Interpretation:

An expression for the absorbance of a solution containing an indicator has to be calculated.

Concept introduction:

Beer-Lambert’s law states that the intensity of light absorbed by a substance dissolved in a completely transmitting solvent is directly proportional to the concentration of the substance and the path length taken by the light while travelling in the solution.

It is mathematically expressed as,

$A=\text{ log}\left(\frac{I_0}{I}\right)=\epsilon lc$

Where,

$\begin{array}{l}A=\text{ Absorbance}\\ I_0=\text{ intensity of incident radiation}\\ \text{I}\text{= intensity of trasmitted radiation}\\ \epsilon \text{= molar extinction co-efficient}\\ \text{l}\text{= pathlength of the light}\\ \text{c}\text{= concentration of the solution}\end{array}$

(b)

Interpretation Introduction

Interpretation:

pK_a for this indicator has to be calculated.

Concept introduction:

Beer-Lambert’s law states that the intensity of light absorbed by a substance dissolved in a completely transmitting solvent is directly proportional to the concentration of the substance and the path length taken by the light while travelling in the solution.

It is mathematically expressed as,

$A=\text{ log}\left(\frac{I_0}{I}\right)=\epsilon lc$

Where,

$\begin{array}{l}A=\text{ Absorbance}\\ I_0=\text{ intensity of incident radiation}\\ \text{I}\text{= intensity of trasmitted radiation}\\ \epsilon \text{= molar extinction co-efficient}\\ \text{l}\text{= pathlength of the light}\\ \text{c}\text{= concentration of the solution}\end{array}$