required practical 7- chromatography to investigate pigments in leaves

method

draw pencil line 1cm from bottom of paper. cut section of leaf and grind in pestle and mortar to release the pigments. use capillary tube to extract some pigment and blot onto centre of pencil line. suspend paper in solvent- solvent below pencil line. allow solvent to run up until near the top. remove paper from solvent and draw pencil line where solvent moved to. pigment should be separated at different heights. calculate rf value at each spot- distance travelled by solute/ distance travelled by solvent. measure centre of spot

what are the 3 risks in this practical and how to prevent

biohazard- contamination/allergies. wash hands after use. solvent- irritation to eyes. wear eye protection. acetone- drowsiness if inhaled, keep room well ventilated

why must the line be pencil?

so ink doesnt effect the results

factors that affect the rate of mobliity

affinity- pigments have different affinities, lower affinity = travel further up paper. solubility- more soluble travel faster up paper and end up closer to the top