required practical 7: use of chromatography to investigate pigments isolated from leaves Flashcards
1
Q
describe how leaf pigments are isolate from a leaf
A
crush leaves with solvent to extract pigment.
draw a pencil line on chromatography paper 1cm above bottom.
add a drop of the extract to the line
stand paper in boiling tube with solvent below the start line.
add lid.
remove paper before solvent reaches the top of the paper.
2
Q
why is the origin drawn in pencil rather than ink
A
the ink is soluble in solvent so would mix with the pigments/move from origin
3
Q
why is the point of origin above the solvent
A
pigments are soluble in the solvent, so would dissolve
4
Q
why may certain pigments not move from origin
A
they are only soluble in certain pigments
5
Q
how are pigments identified
A
work out Rf value
compare Rf value to data book value
