Modern Analytical Tecnhiques

Question 1

What is Mass spectrometry ?

Answer 1

Analytical technique used to identify unknown compounds

Question 2

How is an M+ ion made?

Answer 2

Molecules in sample are bombarded with electrons , which remove electrons from molecule to form molecular ion (M+)

Question 3

How does fragmentation occur of a M+ ion? What is this useful for?

Answer 3

M+ ion can fragment to form new ions, molecules and radicals
- fragmentation patterns can be used to identify molecules and structure

Question 4

How can mass spectrometry be used to differentiate between similar molecules?

Answer 4

• molecule may have same Mr but different structures , so produce different fragments, which show on mass spectrum

Question 5

What is infrared spectroscopy?

Answer 5

Techniques used to identify compounds based on changes in vibrations of atoms when they absorb IR of certain frequencies

Question 6

When molecules absorb IR radiation , what are the 3 ways bonds can vibrate?

Answer 6

STRETCHING
BENDING
TWISTING

Question 7

What is resonance frequency?

Answer 7

the specific frequency at which the molecules will vibrate to stimulate larger vibrations

Question 8

How can IR spectroscopy be used to identify molecules?

Answer 8

• graph is produced showing what frequencies of radiation molecules are absorbing
• can identify functional groups
  Peaks show where radiation is being absorbed

Question 9

What is wave number?

Answer 9

Measure used for frequency
- 1/wavelength

Question 10

What is mass swpcyromertry used for?

Answer 10

• Can be used to find relative abundance of isotopes
• differentiate between similar molecules
• identify unknown molecules /their structure