Practical 7

Question 1

what is the purpose of chromatography

Answer 1

to separate different components in a sample

Question 2

state the factors affecting the rate of migration of different pigments

Answer 2

solubility
mass
affinity to the paper

Question 3

what is the formula of RF value

Answer 3

distance moved by pigment/ distance moved by solvent

Question 4

what is the purpose of finding the RF value of a pigment

Answer 4

experimental RF value can be compared to a standard value in a database to identify the pigment. the standard value should be measured using the same paper and solvent

Question 5

outline the procedure of using chromatography to separate photosynthetic pigments

Answer 5

1. draw a horizontal pencil line 1cm above the bottom of the filter paper
2. add some acetone and use the mortar and pestle to grind up the leaf sample and release the pigments
3. use a capillary tube to transfer the pigment onto the pencil line
4. suspended the paper in the solvent so that the level of the liquid does not lie above the line and leave the paper util the solvent has ru up the paper to near the top
5. remove the paper from the solvent and draw a pencil line marking where the solvent moved up to
6. calculate the RF value of each spot

Question 6

state the hazards and precautions in this practical

Answer 6

solvents are irritant and flammable. keep away from naked flames, wear eye protection and avoid contact to skin,
leaf extract may be a biohazard. wash hands after use

Question 6

state the hazards and precautions in this practical

Answer 6

solvents are irritant and flammable. keep away from naked flames, wear eye protection and avoid contact to skin,
leaf extract may be a biohazard. wash hands after use