C1 : Chromatography

Question 1

Paper chromatography

Answer 1

Allows us to separate substances based on their solubility’s

Question 2

How does it work

Answer 2

. Take a piece of chromatography paper and draw a pencil line near the bottom
. Put a dot of color A on the pencil line and but color B next to it
. Place the bottom of the paper into a solvent (liquid that dissolves substances)
. Solvent moves up paper dissolving ink of the dots
. If the dots separate into multiple spots, it tells us it is a mixture
. If it doesn’t, it’s a compound
. A more soluble substance travels further up the paper

Question 3

Phases

Answer 3

Paper is the stationary phase as it does not move
Solvent is the mobile phase as it does move

Question 4

Why do we draw our starting line in pencil

Answer 4

The pen would ink the paper with the solvent

Question 5

Using paper chromatography to identify an unknown substance

Answer 5

. Place dot on pencil line and put paper into solvent
. If their is one dot the chemical is pure
. Measure how far the substance moved
. Measure distance moved by solvent
. Calculate Rf value (distance moved by substance / distance moved by solvent)
. Several different substances could have the same Rf value so we might need to repeat the experiment using a different solvent
. If the substance has not been analysed before, there will not be an Rf value on the database