Paper chromotography

Question 1

Why is paper chromatography useful?

Answer 1

it separates substances in a mixture, you can then identify the components

Question 2

What are the 2 phases of chromatography and explain them

Answer 2

-mobile phase where the molecules can move (liquid solvent)
-stationary phase where molecules cant move (chromatography paper)

Question 3

How does chromatography work?

Answer 3

-mobile phase moves through stationary phase
-components spend different amounts of time in the phases: more time in mobile phase means they move further
-time spent in different phases separates the components out

Question 4

How can paper chromatography be used to identify a biological molecule?

Answer 4

-draw pencil line near bottom of paper and place spot of mixture on it.
-add small amount of appropriate solvent into beaker and dip bottom of paper in
-as solvent spreads up, different molecules move at different rates and separate out
-when solvent is almost to top, mark solvent front with pencil and leave to dry
-use Rf values to identify the molecules

Question 5

Considerations to make during this process

Answer 5

-could roll paper into cylinder so it stands
-do in fume cupboard
-use lid to stop evaporation
-spray amino acids with ninhydrin solution to make them visible-fume cupboard and gloves

Question 6

How do you calculate the Rf value?

Answer 6

distance travelled by solute/distance travelled by solvent