Ch.12 IR and Mass Spec

Question 1

Infrared Spectroscopy

Answer 1

Measures the bond vibration frequencies in a molecule and is used to determine the functional group

Question 2

Mass Spectroscopy

Answer 2

Fragments the molecule and measures the masses

Question 3

Nuclear Magnetic Resonance

Answer 3

Spectroscopy detects signals from hydrogen atoms and can be used to distinguish isomers

Question 4

Ultraviolet Spectroscopy

Answer 4

Uses electron transitions to determine bonding patterns

Question 5

What is Frequency?

Answer 5

The number of complete wave cycles that pass a fixed point in a second

Question 6

What is Wavelength ?

Answer 6

Is the distance between any two peaks of the wave

Question 7

Frequency and wavelength are ________ proportional (Directly or Inversely)

Answer 7

Inversely

Question 8

Higher frequency means _____ wavelength (Shorter or longer)

Answer 8

Shorter wavelength

Question 9

For shorter wavelength means ______ frequency (Lower or higher)

Answer 9

Higher

Question 10

For lower frequency, the wavelength is ________ (Longer or shorter)

Answer 10

Longer

Question 11

For longer wavelength, the frequency is ______ (Lower or higher)

Answer 11

Lower frequency

Question 12

What is the wavelength range for the IR region?

Answer 12

2.5 to 25 nanometers

Question 13

What is a wavenumber?

Answer 13

The reciprocal of wavelength

Question 14

What are the units of wavenumber?

Answer 14

1/cm

Question 15

Wave numbers are proportional to what two things?

Answer 15

1. Frequency 2. Energy

Question 16

In molecular vibrations, if the bond is stretched, a restoring force pulls the two atoms __________ (Together or Apart)

Answer 16

Together

Question 17

In molecular vibrations, if a bond is compressed, a restoring force pulls the two atoms ______ (Together or Apart)

Answer 17

Apart

Question 18

The atoms vibrate when a bond is _____

Answer 18

Stretched or Compressed

Question 19

Covalent bonds absorb energy according to what 3 things?

Answer 19

1. Polarity 2. Bond strength 3. Molar mass

Question 20

Frequency _______ with increasing atomic mass (increases or decreases)

Answer 20

Decreases

Question 21

What is Spectroscopy?

Answer 21

An analytical technique which helps determine a structure

Question 22

Frequency ______ with increasing bond energy (increases or decreases)

Answer 22

Increases

Question 23

Nonlinear molecule with n atoms usually has _________ fundamental vibrational modes

Answer 23

3n-6

Question 24

Can two molecules give the exact same IR?

Answer 24

No, except enantiomers

Question 25

What is the range for simple stretching?

Answer 25

1600 to 3500 cm-1

Question 26

What is the range for complex vibrations?

Answer 26

600 to 1400 cm-1

Question 27

A polar bond is usually IR ______ (Active or inactive)

Answer 27

Active

Question 28

Stronger carbon carbon bonds absorb at _______ frequencies Higher or lower

Answer 28

Higher frequencies

Question 29

Why the stronger carbon carbon bonds absorb at higher frequencies?

Answer 29

Because the bond is difficult to stretch

Question 30

Does conjugation in C-C bonds lower or increases the frequency?

Answer 30

Lowers

Question 31

A greater percent of s character in the hybrid orbitals will make the C-H bond\_\_\_\_\_\_\_ (Stronger or Weaker)

Answer 31

Stronger

Question 32

The C-H bond of an sp3 carbon will be slightly _________ than the C-H bond of an sp2 or an sp carbon (weaker or stronger)

Answer 32

Weaker

Question 33

[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/021/589/452/q_image_card.jpg?1360681596)

Answer 33

[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/021/589/452/a_image_card.jpg?1360681613)

Question 34

what is Spectroscopy?

Answer 34

an analytical technique which helps determine a structure