Modern Analytical Techniques

Question 1

Steps of mass spectrometry

Answer 1

Inject sample
Vaporise sample
Ionise sample with electron gun to form +1 ion
Accelerate and focus sample with electric field
Deflect sample with strong electromagnet
Detective ions with ion counter

Question 2

How does fragmentation work in mass spectrometry

Answer 2

Molecules bombarded with electrons ionises them and splits them into fragments that are picked up in the mass spectrum

Question 3

Order of stability of carbocations

Answer 3

3•>2•>1•

Question 4

How are different molecules identified in a mass spectrum

Answer 4

Unique fragmentation pattern that can be compared to computer data bases

Question 5

What does high resolution mass spectroscopy allow us to do

Answer 5

Measure M/z values to enough accuracy to find molecular formula by using more decimal places

Question 6

How does infrared spectroscopy work

Answer 6

All bonds vibrate at a characteristic frequency which depends on mass of atoms In a bond, bond strength and type of vibration
if infra red light passes through it will absorb light at the frequency at which its bonds vibrate

Question 7

What is the fingerprint region when identifying molecules

Answer 7

Complex absorption pattern that can be identified by comparing against a data base

Question 8

Oh in alcohol on infra red spectroscopy

Answer 8

3350
Broard

Question 9

Oh in acid infra red spectroscopy

Answer 9

3000
Broard

Question 10

C double bond O infra red spectroscopy

Answer 10

1700
Skinny and long

Question 11

C double bond C on infra red spectroscopy

Answer 11

1650
Skinny and short

Question 12

Ch bond infrared spectroscopy

Answer 12

3000
Jagged

Question 13

Common ion fragment at 15 mz

Answer 13

Ch3+

Question 14

Common ion fragment at 29 mz

Answer 14

Ch3ch2+

Question 15

Common ion fragment at 43 mz

Answer 15

Ch3ch2ch2+

Question 16

Dm3 to m3

Answer 16

Divide by 1000