Topic 7- Modern Analytical Techniques

Question 1

Infrared radiation is absorbed by any…

Answer 1

Polar bond

Question 2

What does absorbed infrared radiation do to bonds?

Answer 2

Makes bonds vibrate

Question 3

Why may C-N bonds not absorb the same frequency as each other?

Answer 3

Because although the same bond, they’re in different environments

Question 4

Name the 4 stages in Mass Spec?

Answer 4

Ionisation
Acceleration
Deflection
Detection

Question 5

How are ions “ionised”

Answer 5

Bombarded with electrons to form positive ions.

Question 6

How are ions accelerated?

Answer 6

High electric potential (field)

Question 7

How does deflection happen?

Answer 7

Powerful magnetic field

Question 8

What does the detection part mean?

Answer 8

Ions of lowest mass detected first.

Question 9

Describe the result of bombarding molecules with high energy electrons?

Answer 9

Leaves fragments with a • or a + (or one fragment with•+)

Question 10

Mass spectrometry only detects the…. (……s are LOST)

Answer 10

Mass spectrometry ONLY detects the + charged ions (radicals are LOST)

Question 11

Which part of the mass spectrometer separates ions of different mass?

Answer 11

The magnetic field.

Question 12

What area is known as the fingerprint region?

Answer 12

Wavenumber below 1500cm-1

Question 13

Which physical methods of chemical analysis are used in modern breathalysers?

Answer 13

Infrared Spectroscopy

Question 14

In mass spectra what does the peak intensity correlate to?

Answer 14

How stable the ion is (very intense peak=very stable)

Question 15

Describe IR spectroscopy

Answer 15

bonds in a molecule absorb infra-red radiation at

characteristic frequencies causing the covalent bonds to vibrate