Chapter 13, Problem 13.15QAP

Interpretation Introduction

(a)

Interpretation:

The percent transmittance and the absorbance of the absorbing solution for the linear readings given by the photometer should be determined.

Concept introduction:

The percent transmittance of a solution is the ability of the solution to allow the monochromatic light to pass through it. The percent transmittance of a solution is the ratio of the intensity of monochromatic light incident on the solution to the intensity transmitted through the solution.

The expression for the percent transmittance for a sample solution is:

$\%T=\left(\frac{P}{P_{\text{o}}}\right)\times 100\%$

The absorbance of the solution is the ability of the solution to absorb the monochromatic light passing through it. The absorbance of the solution is defined as the ratio of the intensity of light incident on the solution to the intensity of light absorbed by the solution.

The relation between the absorbance and transmittance is related by Beer’s law.

$A=-\log \left(\frac{T}{100\%}\right)$

Interpretation Introduction

(b)

Interpretation:

The transmittance of the solution if the concentration of the absorber is reduced to half of the original solution should be determined.

Concept introduction:

The percent transmittance of a solution is the ability of the solution to allow the monochromatic light to pass through it. The percent transmittance of a solution is the ratio of the intensity of monochromatic light incident on the solution to the intensity transmitted through the solution.

The relation between the absorbance and transmittance is established by Beer’s law.

$A=-\log T$

Interpretation Introduction

(c)

Interpretation:

The transmittance of the solution is to be determined if the path length of the light in the cell is doubled.

Concept introduction:

The percent transmittance of a solution is the ability of the solution to allow the monochromatic light to pass through it. The percent transmittance of a solution is the ratio of the intensity of monochromatic light incident on the solution to the intensity transmitted through the solution.

The relation between the absorbance and transmittance is established by Beer’s law.

$A=-\log T$

The absorbance of the solution is directly proportional to the path length of the cell. So, if the path length is doubled, the absorbance of the solution will also be doubled.