Chromatography

Question 1

What 2 chemical phases does chromatography rely on?

Answer 1

Mobile phase, phase that moves and stationary phase, phase that doesn’t move

Question 2

How does gas chromatography work?

Answer 2

The stationary phase is silica or alumina powder packed into a metal column, and mobile phase unreactive carrier gas

Question 3

Thin layer chromatography .

Answer 3

Glass with silica powder in the stationary phase and any solvent for the mobile phase

Question 4

What happens in gas chromatography?

Answer 4

sample - gas state –> carrier gas (mobile phase) pushes it into column packed w silica/alumina powder
- diff components take diff times to travel depending on bond w stationary phase
- detector detects component= sends signal to computer
= chromatogram
(each component = peak)

Question 5

How is the pattern produced in the chromatogram (tlc or paper)

Answer 5

further up = stronger bond w mobile phase

lower down = stronger bond w stationary phase

Question 6

Why is thin layer chromatography better than paper chromatography?

Answer 6

• quicker
• more sensitive = smaller sample can be used
• larger range of stationary phases + solvents

Question 7

What can you tell from a gas chromatogram

Answer 7

If the peaks come at the same time they are most likely the same substance and the higher the peak the more substance

Question 8

Rf value?

Answer 8

Distance substance travelled/ distance solvent travelled.