Chromatography

Question 1

Suggest the two factors that affect how far compounds travel up the chromatography paper

Answer 1

polarity
size of molecule

Question 2

Suggest why an 100% percentage yield cannot be obtained

Answer 2

the reaction is reversible

Question 3

What is meant by the term closed system to do with equilibrium

Answer 3

when no reactants or products can escape

Question 4

What test can be used to distinguish between an alkanal and a ketone

Answer 4

only the aldehyde can oxidise by tollens reagent to form a silver mirror

Question 5

What does it mean when the atom economy is 100%

Answer 5

there are no waste products

Question 6

in chromatography what is the time taken for the component to travel through the appartus called

Answer 6

retention time

Question 7

In chromatography how can the identity of a component be identified

Answer 7

the distance it has travelled
the time it has taken to travel through the apparatus

Question 8

What is meant by retention factor

Answer 8

the distance travelled by the compound compared to the distance travelled by the solvent.

Question 9

State how retention factors could be used

Answer 9

To help identify the components in
a mixture

Question 10

Suggests why there are only three spots in a chromatography

Answer 10

The spots for … overlap
The Rf values are similar for …

Question 11

Explain why different amino acids travel different distances up the chromatography paper

Answer 11

difference in the polarity or size of molecules results in different Rf for different compounds

Question 12

What happens if too much solvent is added

Answer 12

the samples would dissolve in the solvent rather than travel up the paper with the solvent