Warning! This experiment uses fire. Be very careful and be sure an adult is around to help.

This time we are going to explore a gas called carbon dioxide. It plays an important role in the lives of plants and animals, and it has very specific chemical properties. We can use those properties to do some surprising things.

For this experiment, you will need:

- two large bowls or pots
- a short candle
- vinegar
- baking soda
- foil
- a few sheets of newspaper

This experiment will work best in an area where you do not have air from fans, heaters, windows, etc. blowing around. Cover your table top with newspapers, in case you make a mess.

Shape the foil around the bottom of the candle to form a base. This will hold the candle in place without messing up your bowl. Look to be sure that the candle is only about half as tall as the bowl. It if is too tall, cut away part of the base to shorten it

In the other bowl, put about a cup of vinegar. If your bowl is less than 3 quarts, you will want to put in less vinegar, so that it won't foam over and make a mess. Measure out about half a cup of baking soda.

Place the two bowls side by side. Light the candle. Now pour the baking soda into the vinegar. It will bubble and foam quite a bit. DO NOT STIR! Wait for the foam to die down. Now, carefully lift the bowl and hold it over the candle. Act as if your were pouring water from the bowl with the vinegar into the bowl with the candle, but do not pour any of the liquid. After a few seconds, the candle will go out without any visible sign of why.

What happened? When you mixed vinegar and baking soda, it produced carbon dioxide gas. That is what forms the bubbles. Carbon dioxide is heavier than the air around you, so it stayed in the bowl. Then you poured the heavy gas into the bowl with the candle. Even though you could not see it, the gas poured from one bowl into the other. As the level of carbon dioxide rose, it smothered the candle flame.

If you run into problems, there are several things to check. First, be sure and there are no breezes or air currents in the room. Also, be sure that the candle is very short, and that you have enough carbon dioxide to fill the bowl to a depth that is higher than the candle.