Analytical techniques I & II

Question 1

What is NMR spec

Answer 1

an analytical technique that allows the structure of a molecule to be determined by analysing bond & atom environments.

Question 2

What is an environment of an atom

Answer 2

the surrounding atoms and bonds in the molecule.

Question 3

What is the molecular ion peak

Answer 3

a mass spectrometer trace is the whole compound as an ion (so gives Mr), lies furthest to the write

Question 4

What is the fingerprint region used for

Answer 4

can be used as a comparison to identify something.

Question 5

When does fragmentation occur

Answer 5

occurs when molecules break into smaller pieces in a mass spectrometer.

Question 6

Steps of using a mass spectrometer

Answer 6

VIADD
- vaporisation
- ionisation
- acceleration
- deflection
- detection

Question 7

How does chromatography work

Answer 7

Substances are separated according to a relative affinity to stationary and mobile phases

Question 8

What is the mobile phase of a chromatogram

Answer 8

The solvent/inert gas

Question 9

What is the stationary phase of a chromatogram

Answer 9

the powder (SiO2) or paper

Question 10

How do you set up a paper/TLC chromatography

Answer 10

• draw a start line in pencil on the plate
• spot samples using a capillary tube on the start line, evenly spaced out
• place in a shallow layer of solvent that does not exceed the origin line
• put a lid on the beaker
• wait until the solvent nearly reaches the top
• mark the ‘solvent front’ on where the solvent stopped moving

Question 11

How do you calculate an Rf value

Answer 11

distance travelled by the substance / distance travelled by the solvent

Question 12

If a substance in polar and is placed in a chromatogram with a non polar solvent and non polar, how fast does it move

Answer 12

it will move slower up the chromatogram