Chromatography

Question 1

What do chromatographic separations depend on?

Answer 1

the partition equilibrium between two phases, one stationary phase and the other mobile.

Question 2

Describe paper chromatography.

Answer 2

the stationary phase is the water on the paper and the mobile phase is another solvent or solvent mixture.

Question 3

Describe thin layer chromatography.

Answer 3

the stationary phase is a thin layer of aluminium oxide or silica gel on a glass plate or aluminium sheet and a solvent or solvent mixture is the mobile phase. Separation is much quicker than in paper chromatography

Question 4

What kind of measurement do paper and thin-layer chromatography rely on?

Answer 4

measurements of Rf values for the identification of the components of a mixture

Question 5

What is the retention time said to be for any given compound in a particular solvent mixture?

Answer 5

constant

Question 6

What can Rf values be compared to?

Answer 6

published values

Question 7

What is the equation to calculate Rf?

Answer 7

Rf = Distance moved by solute/ Distance moved by solvent