Lab: IR Spectroscopy Part One

Question 1

absorption occurring at BLANK wavenumbers require less energy than those at BLANK wavenumbers

Answer 1

Low; high

Question 2

higher wavenumber = BLANK wavelength

Answer 2

lower

Question 3

higher wavenumber = BLANK energy

Answer 3

higher

Question 4

functional group region

Answer 4

4000-1400 cm-1

Question 5

fingerprint region

Answer 5

1500-400 cm^-1

Question 6

larger frequencies (higher energies) are absorbed by

Answer 6

• bonds with a higher bond order (triple>double>single)
• bonds between atoms with larger mass differences

Question 7

Approximate stretching frequency of O-H and N-H

Answer 7

3250 cm^-1

Question 8

Approximate stretching frequency of C-H

Answer 8

3000 cm^-1

Question 9

Approximate stretching frequency of C ||| N and C ||| C

Answer 9

2250 cm^-1

Question 10

Approximate stretching frequency of C=O

Answer 10

1715 cm^-1

Question 11

Approximate stretching frequency of C=C

Answer 11

1600 cm^-1

Question 12

Describe the typical peak of O-H

Answer 12

strong to moderate and broad

Question 13

Describe the typical peak of N-H

Answer 13

moderate to weak and sharp

Question 14

Describe the typical peak of alkyne C-H

Answer 14

very sharp

Question 15

Approximate stretching frequency of saturated (sp³) C-H

Answer 15

below 3000 cm^-1

Question 16

Approximate stretching frequency of unsaturated (sp²) C-H

Answer 16

above 3000 cm^-1

Question 17

Approximate stretching frequency of an aldehyde

Answer 17

2750 and 2850 cm^-1

Question 18

Describe the typical peak of alkyne C|||C

Answer 18

moderate to weak

Question 19

Describe the typical peak of nitrile C|||N

Answer 19

strong to moderate

Question 20

Describe the typical peak of C=O

Answer 20

strong and slightly broad

Question 21

An important thing to remember about C=O

Answer 21

It is highly influenced by other functional groups and has a large range of 1800 to 1650 cm^-1

Question 22

Describe the typical peak of C=C

Answer 22

strong to moderate and sharp

Question 23

Approximate stretching frequency of aromatic C=C

Answer 23

below 1600 cm^-1

Question 24

Approximate stretching frequency of alkene C=C

Answer 24

above 1600 cm^-1

Question 25

It is helpful to draw in the approximate zone lines which are

Answer 25

• 3200 cm^-1
• 2700 cm^-1
• 2000 cm^-1
• 1650 cm^-1
• 1400 cm^-1