Chromatography - 7

Question 1

Use of chromatography to investigate pigments isolated from leaves of different plants e.g leaves from shade-tolerant and shade intolerant plants or leaves of different colours.

Question 2

State the equipment used in this practical

Question 3

Describe the method?

Answer 3

1. Take a piece of chromatography paper, thin enough to fit into a boiling tube
2. 2cm pencil line at bottom of filter paper - line of origin
3. Cut a disc from leaf A and Lef B - try to avoid the midrib and the leaf stalks.
4. Place the disc on the chromatography paper at centre of the origin line
5. Crush the pigment onto the chromatography paper using a glass rod
6. Place 3cm3 of solvent into a boiling tube.
7. Pin the top of the chromatography paper to the top of the bung and leave to sit in the solvent until the solvent reaches the solvent front.
8. The fitler paper should have a series of spots that go up the chromatogram.
9. Let to dry and then calculate Rf values for each pigment on the chromatogram.

Question 4

How is the Rf value calculated?

Answer 4

Rf - Distance moved by pigment from origin to centre of pigment spot/ Distance from origin to solvent front

Question 5

What are some risks Associated with this practical?

Answer 5

solvent - Flammable - keep away from naked flames and wear goggles
Drawing pin - sharp - can prick you
Boiling tube - glass - can break

Question 6

Include some exam Q’s