Chemical Heat

Here's an experiment that shows how a common chemical reaction creates heat. See if you can figure out what the reaction is.

You'll need a good-sized jar with a lid, a small thermometer that will fit in the jar, some steel wool (plain steel wool, not the scrubbing pads that contain soap), and vinegar.

First, take a handful of steel wool, and place it in the jar. Put the thermometer in, making sure that the bulb (temperature-sensing part) in surrounded by steel wool. Record the temperature. Wait a few minutes, then check again. Boring, huh? The temperature shouldn't change very much.

Now for some chemistry! Take the thermometer and steel wool out of the jar. Soak the steel wool in vinegar for a few minutes, then remove it and squeeze the vinegar out (wear a rubber glove when doing this). Quickly put the steel wool and thermometer back in the jar the way it was before. Watch the thermometer for several minutes. Does anything happen? Check back a few times over the next hour or so. What happens to the temperature? Does the steel wool look the same? What do you think happened to it? Here's a hint: don't get distracted by the vinegar - it's not involved in the reaction.