Topic 27- Chromatography

Question 1

Thin layer chromatography: Stationary and mobile phase

Answer 1

Stationary: Silics/ Alumina
Mobile: Water/ General solvert

Question 2

TLC advantages and disadvantages

Answer 2

-Faster than paper
- Easy method
- Small amounts needed
-Results difficult to reproduce
- There are longer plates than TLC
- Temperature and humidity affect results

Question 3

Methods of revealing spots on TLC paper

Answer 3

Shining UV light
Expose the chromatography plate to iodine vapour

Question 4

Collumn chromatography stationary and mobile phase

Answer 4

Stationary: Aluminium oxide coated with water
Mobile phase: General solvent

Question 5

Collumn chromatography advantages and disadvantages

Answer 5

• Large amounts can be separated
• They can easily be obtained
• Takes more time to separate compounds
• More solvent is required so its more expensive

Question 6

All amino acids show optical activity except for

Answer 6

Glycine

Question 7

Overview of Gas chromatography method

Answer 7

Gas injected into oven
Nitrogen is passed through as carrier gas
Stationary phase Is solid or solid covered in liquid
Different gases will have different retention times

Question 8

What is gas chromatography good for?

Answer 8

Volatile liquids

Question 9

Advantages/disadvantages of gas chromatography

Answer 9

Very sensitive
Some compounds have similar retention times so cannot be distinguished
‘Unknown’ substances have unknown retention times