Thursday, January 14, 2010

M&M Science

Here's a cool science experiment we did last night.

Put 5 or 6 different colors of M&M's in a glass with a small amount of water. Stir around until the color comes off. Note that the water will be all one color – remove the M&M’s and stir until colors are all dissolved into one color – usually something grayish. Spoon out the M&M remains.

Point out that the colors seem to have all blended together – the bright colors seem to have disappeared. Now I like M&M's, but this "soup" doesn't look very appetizing!

Take a coffee filter (or a paper towel) and cut a strip long enough to reach down into the water. You can staple the top edge to make a loop that you can hang from a pencil. Make sure the paper reaches down to touch the water.

Leave it overnight, the various colors will separate on the paper, showing that they really didn’t disappear into a single color. I think we would have a better rainbow if we didn't put brown M&M's in the water.

Here’s the science behind it: because molecules in ink or the colored coating on M&M’s have different characteristics, such as size and solubility, the travel at different speeds when pulled along a piece of paper by a solvent (the water). For example, the grayish water color, contain several colors. The water soluble colors behave differently due to their molecules, and separate into a sort of “rainbow” of colors.

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