Today we were detectives and used paper chromatography to separate the dyes of various colors of M&M candies. Paper chromatography is a separation technique in which dots of pigment, in our case food dye, are placed on special filter paper and the paper is then dipped into a solvent. We used a simple solution of salt water (4 c. water + 1/8 tsp. salt) as the solvent, and as the salt water traveled up the paper, it dissolved the dots of food dye and carried them along with it. The individual colors that make up the food dyes get spread out on the paper because they have different affinities to the paper. At the end of the experiment, we took the papers out of the alcohol and these were our chromatographs.
Ask your child about the dyes that make up green & brown M&Ms! This simple experiment can be repeated with different candies (such as Skittles) and coffee filters cut into strips can be used in place of special chromatography paper.
We’ve had a wonderful year doing science experiments with your children. We wish you a happy summer full of curiosity & exploration and best of luck to every one going into 6th grade next year!