✅7 - Modern Analytical Techniques I

Question 1

What is mass spectrometry used for?

Answer 1

Identifying compounds

Question 2

What is the molecular ion, M+?

Answer 2

The molecule with an electron removed

Question 3

What is the molecular ion peak?

Answer 3

The peak with the highest m/z value

Question 4

What does the Molecule ion peak show?

Answer 4

The relative formula mass of the compound

Question 5

What can the molecular ion be broken into?

Answer 5

Smaller fragments

Question 6

What is a fragmentation pattern?

Answer 6

The mass spectrum shown by all the fragments

Question 7

How can fragments be identified?

Answer 7

By their molecular mass

Question 8

What is mass spectrometry used to differentiate between?

Answer 8

Similar molecules

Question 9

How is Infrared spectroscopy carried out?

Answer 9

A beam of IR radiation is passed through a sample of a chemical

Question 10

How does the IR radiation affect bonds?

Answer 10

It is absorbed by covalent bonds in the molecules, increasing their vibrational energy

Question 11

How can IR spectroscopy be used to differentiate between bonds?

Answer 11

Bonds between differnet atoms absorb different frequencies of IR radiation

Question 12

How does the location of a bond affect its absorption?

Answer 12

In the frequency absorbed, so OH groups on alcohols and carboxylic acids have different frequencies of absorption

Question 13

What does in infrared spectrometer produce?

Answer 13

A graph

Question 14

What is plotted on the y axis of an IR graph?

Answer 14

Transmittance

Question 15

What is plotted on the x axis of an IR graph

Answer 15

Wavenumber - 1/wavelength in cm

Question 16

How can IR spectroscopy show if a reaction has happened?

Answer 16

If the functional group has changed on the graph

Question 17

How would an IR spectroscopy graph change if an alcohol was oxidised to an aldehyde?

Answer 17

The O-H absorption would disappear and and C=O would appear

Question 18

How would an IR spectroscopy graph change is an aldehyde was oxidised to a carboxylic acid?

Answer 18

The O-H peak would appear at a slightly lower frequency and the C=O peak will remain

Question 19

What does IR radiation cause covalent bonds to do?

Answer 19

Vibrate

Question 20

What do the peaks on the IR graph show you?

Answer 20

Where the radiation is being absorbed