Chromatography Flashcards
1
Q
What is the purpose of chromatography?
A
To separate a mixture of soluble substances based on their solubility, and to identify them
2
Q
In chromatography, what is a ‘mobile phase’?
A
Where the molecules can move
3
Q
In chromatography, what is a ‘stationary phase’?
A
Where the molecules cannot move
4
Q
What is the stationary phase in paper chromatography?
A
The piece of paper
5
Q
What is the mobile phase in paper chromatography?
A
The solvent
(e.g. water or ethanol)
6
Q
Describe the process of using paper chromatography to separate a mixture of soluble substances.
A
- Draw the baseline near bottom of paper - put a spot of the mixture to be separated on the line
- Put some of the solvent into beaker, and dip the paper in so the solvent is just beneath where the spot is
- Put a watch glass on top of beaker to stop any solvent evaporating away
- Solvent will move up paper - when chemicals in mixture dissolve in solvent, they will move up too
- (Each spot formed will represent different chemicals)
- Remove paper from beaker before solvent reaches top - mark in pencil the distance travelled by solvent (solvent front)
7
Q
Why is it important that the baseline on the paper is drawn with a pencil?
A
Pencil markings are insoluble, and they won’t move with the solvent
