Question

Indicate which of the following statements about the electromagnetic spectrum and IR spectroscopy are true and which are false. In any cases where the statement is false, explain how or why the statement is false.

1. Infrared (IR) light is in the gamma ray part of the electromagnetic spectrum.               
2. Electromagnetic radiation is characterized by its mass and force.
3. UV-Vis spectra are normally scanned in the 4000-600 cm-1 region.
4. The fingerprint region on an IR spectrum is the easiest to interpret.
5. Stronger bonds absorb IR light at higher wavenumbers than weaker bonds.
6. In the IR spectrum of methanphetamine there will be two C=O signals because aspirin contains both an acid and an ester.
7. It is impossible to obtain structural information from an IR spectrum by noticing which absorptions are absent.
8. The C-O bond absorbs IR radiation of a lower energy than the C=O bond because it has a lower reduced mass.
9. It is impossible to obtain structural information from an IR spectrum by noticing which absorptions are absent.
10. The C-O bond absorbs IR radiation of a lower energy than the C=O bond because it has a lower reduced mass.

Answer 1

a. FALSE- Infrared has frequency in the region of Hz where frequency of Gamma ray appear at Hz.

b. FALSE- Electromagnetic radiation is a wave in nature,so it is charaterized by wavelike properties such as frequency,wavelength etc.

c. FALSE- UV spectra has wavenumber between 25000-50000 cm-1 and visible light has spans from 12000-25000 cm-1.

d. TRUE- The Fingerprint region in IR contains the functional groups with unique charateristics,so they are quite easy to interpret.

e. TRUE - Stronger bonds are more stiff and require much more force to vibrate than weaker bonds .So the Stronger bonds have much more frequency than weak bonds.As frequency is directly proportional to the wavenumber,so stronger the bond,higher the wavenumber.

f. TRUE- Aspirin contains two peaks ,1754cm-1 for the Carbonyl of Ester part and 1693cm-1 for the carbonyl of Acid .

g.TRUE- Studying IR spectra one can get information about functional groups if one notice which absorptions are present.

h. FALSE- reduced mass is same for both the bonds as atoms are same. bond is stronger than so the former has higher energy than the latter.

i. TRUE

j. FALSE