Topic 1: IR Spectroscopy

Question 1

What is wavenumber proportional to?

Answer 1

frequency and energy

Question 2

What is wavelength indirectly proportional to?

Answer 2

wavenumber, frequency, and energy

Question 3

Stronger bonds result in ______ frequency vibrations

Answer 3

lower

Question 4

Lighter atoms at the end of the bonds results in _____ frequency vibrations

Answer 4

lower

Question 5

What region do you look at to gather clear information?

Answer 5

above 1400 cm^-1, functional group and aromatic overtone region

Question 6

What is 400-1400 cm^-1 referred to as?

Answer 6

The fingerprint region

Question 7

Where are single bonds located on IR Spectroscopy?

Answer 7

The fingerprint region (1600cm^-1 and below)

Question 8

Where are double bonds located on IR Spectroscopy?

Answer 8

Between 1600 and 1850 cm^-1

Question 9

Where are triple bonds located on IR Spectroscopy?

Answer 9

Between 2100 and 2300 cm^-1

Question 10

Where are bonds to H located on IR Spectroscopy?

Answer 10

Between 2700 and 4000 cm^-1 (C-H < N-H < O-H)

Question 11

What bonds are very easy to see? What are some examples?

Answer 11

Strong and/or broad; O-H, C-O, N-H

Question 12

What is the intensity of the signal is proportional to?

Answer 12

The amount of light absorbed and the dipole moment

Question 13

____ cm^-1 is the line between alkane and alkene/alkyne C-H bond signals

Answer 13

3000

Question 14

______ alkenes are easier to see due to decreased symmetry because asymmetry causes more of a dipole moment

Answer 14

terminal

Question 15

Only _____ alkynes are easily detectable

Answer 15

terminal

Question 16

Aromatic rings usually portray 4 low-intensity peaks in the _____________ region

Answer 16

aromatic overtone

Question 17

O-H stretch is very _____ and easily seen around ______ cm^-1

Answer 17

broad; 3400

Question 18

N-H is _____ and seen around ______ cm^-1

Answer 18

broad; 3350

Question 19

A primary amine (NH2) has __ hump(s)

Answer 19

2

Question 20

A secondary amine (NH) has __ hump(s)

Answer 20

1

Question 21

A tertiary amine (N) has __ hump(s)

Answer 21

0

Question 22

Carbonyl (C=O) bonds appear around ____ cm^-1

Answer 22

1700

Question 23

Ketones appear around ____ cm^-1 and have no C-H signals around 3000 cm^-1

Answer 23

1715

Question 24

Aldehydes appear around _____ cm^-1 and have characteristic C-H signals at 2840 and 2710 cm^-1

Answer 24

1735

Question 25

Carbonyl bonds for carboxylic acids appear at _____ cm^-1 and the broad O-H signal for carboxylic acids ranges over ____ - ____ cm^-1 (overlapping with C-H bonds)

Answer 25

1715; 3600-2400

Question 26

Carbonyl bonds of esters are at ____ cm^-1 with no NH bonds

Answer 26

1740

Question 27

Carbonyl bonds of amides are at ____ cm^-1 and have N-H bonds around _____ cm^-1 on primary and secondary amides

Answer 27

1700; 3300

Question 28

Why are Nitriles (CN triple bonds) confused with terminal alkynes?

Answer 28

They both appear around 2000 cm^-1 , but nitriles should appear more intense because it is more polar

Question 29

Nitrile signals appear around _____ cm^-1

Answer 29

2200

Question 30

Alkyne signals appear around _____ cm^-1

Answer 30

2100