RP7- CHROMATOGRAPHY LEAVES Flashcards
why should you not use pen to mark the origin
So that the ink and pigments don’t get mixed up
why is it necessary to draw the lie to show the solvent front BEFORE the pigment has dried
cant see the solvent front
Why is it better to compare Rf values rather than distance pigments moved
solvent moves different distances
Rf value is distance moved by pigment ./. distance moved by solvent
why should you not move the solvent bottle after placing the paper in
pigment/solvent would not run straight
why should you measure to the the centre of the pigment spot
centre shows mean distance moved by pigment
allows comparisons to be made
why are xerophytic plants not used for this practical
has a thicker cuticle
so pigment cant transfer on paper
leaves change colour in autumn due to loss of chlorophyll. describe how you would use chromatography to show that chlorophyll is lost
carry out chromatography at different times
find Rf for chlorophyll and compare with the autumn leaves
look for green substance
describe method used to separate the pigments after solution of pigments have been applied to the origin
solvent should be below the line
remove before solvent reaches the top
