Chromatography

Question 1

What is the purpose of chromatography?

Answer 1

Separate different components in a sample

Question 2

State the factors that effect the migration of different pigments

Answer 2

Solubility

mass

affinity for paper

Question 3

Rf value formula

Answer 3

Distance moved by solute / distance moved by solvent

Question 4

What is the point of finding the RF value?

Answer 4

Can be compared to a standard value in a database to identify the pigment

Question 5

Procedure of using chromatography to separate photosynthetic pigments

Answer 5

1. Pencil line 1cm above bottom of paper
2. Acetone and use pestle and mortar to grind up leaf sample to release pigments
3. Use capillary tube to transfer pigment onto pencil line
4. Paper into solvent, water not above pencil line
5. Remove paper from solvent and draw pencil line to where solvent moved to
6. Calculate RF values

Question 6

What is the purpose of using acetone?

Answer 6

Dissolves many organic molecules.

Question 7

Hazards when doing a chromatography practical

Answer 7

Solvents are irritants and flammable

Leaf extract might me a biohazard

Question 8

Why should the final locations of pigments be marked?

Answer 8

The pigments may also disappear as the solvent dries

Question 9

When separating amino acids what must be done?

Answer 9

Paper should be dried and then sprayed with ninhydrin solution, this makes the spits a blue-violet colour

Question 10

What does a small RF value indicate?

Answer 10

Pigment is less soluble and larger