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Spoonful of Sugar

December 6, 2005

Most people wouldn’t think of water as being sticky. But chemists do.

Transcript

BOB HIRSHON (host):
Why sugar sticks to your spoon. I’m Bob Hirshon and this is Science Update.

Have you ever noticed that, if you use the sugar spoon to stir your coffee and then put it back, sugar will stick to the spoon? Well, Neil Savage of Lowell, Massachussetts, wants to know—why doesn’t sugar stick to a dry spoon?

Chemist Joe Merola of Virginia Tech says water—in the form of coffee, in this case—is actually a very good glue. A water molecule has a positively charged side—which attracts the metal on the spoon—and a negatively charged side—which attracts the sugar—making them stick together. In fact, water can make lots of things stick together.

JOE MEROLA (Virginia Tech University):
Paper—if you try to stick it to a wall—won’t stick, but if you wet it it would usually stick. Then when it dries it’ll right off again.

HIRSHON:
Much like the sugar on the spoon. If you have a science question, call us at 1-800-why-isit. I’m Bob Hirshon,