Chromatography Experiments

These two experiments are variations on the same theme - using a solvent (in this case, water) to separate out the different portions of a solute (e.g., ink particles or food coloring particles). The principle is the same in all three cases. At the molecular level, smaller, hydrophilic molecules migrate faster through the paper. Hydrophilic means a "water-loving" substance, as opposed to hydrophobic compounds which are not soluble in water. As well, molecules which are bigger (have a larger mass) move slower along the paper. So the colors left closest to the original start point are made of heavier molecules than those which move further away.

Coffee Filter Chromatography


glasses or clear plastic cups
coffee filters
really cheap markers


1) Put about 1 cm of water into the bottom of the glass.
2) Cut a rectangular piece of the coffee filter.
3) Holding the filter paper outside the glass, use the pencil to mark a line on the filter just above the waterline on the glass.
4) Take a cheap marker and put a SMALL dot of color on the marked line.
5) Place the filter paper into the glass, so that the marker dot is just above the water line.
6) Let it sit for 5-10 minutes.

Bottled Rainbows


1 square of paper towel
clear plastic cup
liquid food coloring
scotch tape


1) Cut a strip of paper towel about an inch wide and about as long as the cup is tall.
2) Tape one end of the strip to the pencil.
3) Place a drop of food coloring about an inch from the opposite end of the strip.
4) Pour about 1/4 of an inch of water into the cup.
5) Balance the pencil on top of the cup so that the paper hangs down into the water, but the drop of coloring must be above the water.
6) Wait until the water soaks the towel almost to the pencil. Remove and set on a paper towel to dry and be observed.

Return to Science and Technology Page

Becky's Guiding Resource Centre Main Menu