Chromatography

Question 1

Why do substances in the mixture separate in the mobile phase?

Answer 1

Different solubilities
Different attractions for the paper

Question 2

How many spots will be produced on a chromatogram of a pure compound?

Answer 2

1

Question 3

Conducting a chromatography assessment

Answer 3

• draw a pencil line
• near the bottom edge of the (chromatography) paper • put a small dot of black ink on the pencil line
• put a small volume of water / solvent in a beaker
• place the (chromatography) paper in the solvent
• the dots of ink should be above the level of the water / solvent • support the paper in this position
• put a lid on the beaker
• leave to run
• mark position of solvent front
• remove from beaker and leave to dry
• determine Rf values
• measure distance of all dots from start line
• measure distance of solvent front from start line • calculate Rf values for all dots
• compare with known Rf values

Question 4

Describe a test to confirm that distilled water is pure

Answer 4

Determine that it boils at 100 degrees