Chapter 3, Problem 42P

Interpretation Introduction

Interpretation:

1. The IR absorption monitored during analysis for CO is at 2143${\text{cm}}^{\text{-1}}$, the diagram of the vibrational mode that gives rise to the absorption is to be drawn.

2. The presence of ${\text{CO}}_{\text{2}}$ interfere with detection of CO is to be explained.

3. 78% of earth’s atmosphere is ${\text{N}}_{\text{2}}$ and fundamental stretching mode gives rise to an absorption at 2359 ${\text{cm}}^{\text{-1}}$, this absorption is not interfere with CO analysis by IR spectroscopy is to be explained.

4. By referring to chapter 29, CO is toxic is to be explained.

5. The number of molecules of CO present in 1${\text{dm}}^{\text{3}}$ of air containing 0.20$\text{mg}{\text{m}}^{\text{-3}}$ CO is to be calculated.

Concept Introduction:

Raman and infrared (IR) spectroscopies are branches of vibrational spectroscopy.

Vibrational spectroscopy is concerned with the observation and determination of number of the degrees of vibrational freedom.

The degrees of vibrational freedom depends on the number of atoms in molecule and shape of the molecule.

For a linear molecule containing n atoms, the number of degrees of vibrational freedom can be determined by the equation:

Number of degrees of vibrational freedom = 3n - 5

For non-linear molecule containing n atoms, the number of degrees of vibrational freedom can be determined by the equation:

Number of degrees of vibrational freedom = 3n - 6