Purpose: To separate food colorings into their component dyes using paper chromatography. Materials: Chromatography paper, Food coloring, Ruler, Pencil, Solvent solution, Test tubes, Test tube rack. Safety precaution: wear aprons, to make sure that you don’t get any of the alcohol on your clothes, and if you break a test tube you don’t get glass on you. Procedure: See-attached handout.
Results: See chromatography with Audrey’s lab report.
Rf values for approved FD & C dyes DyeRf ValueDyeRf Value
Red No. 20.81Yellow No. 60.77
Red No. 30.61Green No. 31.00
Red No. 40.67Blue No. 11.00
Yellow No. 50.75Blue No. 20.79
Rf values for coloring agents in food coloring
Food colorZone colorDistance SoluteDistance solventRfFD&ID Green Yellow2.6 cm6 cm.43
Blue5 cm6 cm.83
BlueBlue7.2 cm7.2 cm1Blue No. 1
YellowYellow2.8 cm6.2 cm.45
Red 4.2 cm6.2 cm.67Red No. 4
Red Red6.5 cm6.5 cm1
Purple4.8 cm6.5 cm.74
Calculation: Distance of the solute/Distance of the solvent
Ex. Yellow 2.6 cm / 6 cm = .43
1.Why do food dyes separate into different colors as they move up the piece of chromatography paper?
Food dyes separate into different colors as they move up the piece of chromatography paper because, when the solution gets absorbed into the paper, it dissolves the color in the ink spot that you have made. Each color that makes up the dye will move at a different speed depending on how strong it gets absorbed as the solution gets absorbed up the paper. 2. Why is it important that ink is not used to mark the lines of the chromatography paper?
It is important to use pencil, because the ink from them pen could also get absorbed by the solution, and it could mess up your experiment. 3. A colored component of a mixture is insoluble in the developing solvent (moving phase), but is...