Ch. 11: Spectroscopy

Question 1

what does spectroscopy measure

Answer 1

energy differences between the possible states of a molecular system by determining the frequencies of electromagnetic radiation absorbed by the molecules

Question 2

what does IR spectroscopy measure

Answer 2

molecular vibrations

stretching, bending, or combinations of different vibrational modes

Question 3

what patterns are seen in the fingerprint region

Answer 3

complex vibrational patterns caused by the motion of the molecule as a whole, characteristic to each individual molecule

1500 - 400 cm-1 range

Question 4

what kinds of bonds are silent in IR spec

Answer 4

atoms with the same electronegativity or symmetry

O2, Br2, C2H2

Question 5

IR absorption for O-H

Answer 5

broad bend at 3300 for alcohols

broad bend at 3000 for carboxylic acids

Question 6

IR absorption for O = H

Answer 6

sharp, deep peak at 1700

Question 7

IR absorption for N-H

Answer 7

sharp peak at 3300

Question 8

how are UV spectra obtained

Answer 8

passing UV light through a sample, recording the absorbance, and plotting against a wavelength

Question 9

what information can be obtained from UV spec

Answer 9

extent of conjugation

Question 10

what kinds of molecules will be represented by the same H-NMR peak

Answer 10

chemically equivalent molecules

Question 11

what does integration of H-NMR peaks respond to

Answer 11

ratio of protons that produce the peak