RP7: Chromatography Flashcards
1
Q
What is the purpose of chromatography?
A
to separate different components in a sample
2
Q
What factors affect the rate of movement of pigments?
A
- solubility
- affinity to paper
- mass
3
Q
What is the formula for the Rf value?
A
distance travelled / solvent front
4
Q
Why are Rf values calculated?
A
so experimental values can be compared to data book values for the same paper and solvent, allowing the pigment to be identified
5
Q
Outline how to carry out chromatography…
A
- pencil line, 1cm up the paper
- using pestle and mortar and acetone, grind up leaf sample
- use a capillary tube to transfer pigment to baseline
- suspend paper in solvent, ensuring solvent does not go above pencil line
- leave until it has run up, near the top
- remove and draw on pencil line at solvent front
6
Q
What 3 factors impact how the pigments travel up the paper?
A
- mass
- solubility
- affinity to paper
7
Q
Why is the line drawn in pencil?
A
as ink and pigments would mix
