Chapter U5, Problem 22STP

Interpretation Introduction

Interpretation:

The correct use of spectroscopy needs to be determined.

Concept introduction:

Spectroscopy is a qualitative analysis technique. It is used to monitor a specific characteristic of products or reactants during a chemical reaction.

Different electromagnetic radiations like Infra-red, Ultra-violet, radio waves, and microwaves are used in this technique.

The interaction of electromagnetic radiation and absorption of certain intensity of light is used to identify the substance present in the given sample.

Answer to Problem 22STP

Option (C) is the correct option.

Explanation of Solution

Reason for correct option: In spectroscopy, the electromagnetic radiations are passed through the sample solution. The change in intensity of radiation is used to determine the intensity of absorbed radiation.

Beer- Lambert law is used to determine the concentration of given sample with the help of spectroscopy method. The mathematical expression of Beer Lambert law is as given below:

$\begin{array}{l}\text{A = }\epsilon \text{ × }l\text{ × C}\\ \text{A = Absorbance}\\ \epsilon \text{ = molarabsorptivity}\\ l\text{ = length}\\ \text{C = concentration}\end{array}$

Conclusion

Reasons for incorrect options: Density and mass of substance can be determined with the help of quantitative analysis. Speed of light cannot measure with the help of spectroscopy method. Thus option (a), (b) and (d) are not correct.