CO2 a heavy gas

What happens when carbon dioxide is poured onto a flame?

Materials Required

• Plastic container (similar to a cottage cheese container)

• Small candle

• Water glass

• Baking soda

• Vinegar

Procedure

1. Place a candle in a cottage cheese container. Light it and let it burn while you prepare the rest of the experiment.

2. Place 1/2 tablespoon of baking soda in the bottom of a water glass

3. Pour 1/4 cup of vinegar into a small container.

4. Pour the vinegar into the water glass with the baking soda. Allow it to mix for a few seconds.

5. Tip the glass toward the candle but be careful to not let any liquid spill out.

Questions

What happens?

Why did the candle go out?

What gas did you pour from the glass?

How did we make that gas?

How do you know that CO2 is heavier than air?

Discussion

This experiment is a classic that can be repeated over and over with good success. We produce carbon dioxide as a by product from the vinegar and baking soda reaction. Here is how it looks as a formula:

               Baking soda    + Vinegar           >>>     Sodium acetate  + water + carbon dioxide

The acid in the vinegar releases the carbon dioxide from the baking soda.  When we pour the carbon dioxide on the flame (when we tip the glass over the candle) it demonstrates two things, 1) the c=gas must be heavier than air so that it falls onto the flame, 2) and we know this because the flame is extinguished. Carbon dioxide will not allow something to burn or oxidize. Oxygen is necessary for something to burn. Instead we have C02 all around the flame and it cannot continue to burn.

CO2 is used to extinguish fires.  Common types of fire extinguishers are made of compressed CO2 gas. When you pull the trigger of a fire extinguisher,  CO2 comes flying out and douses the flames with a gas that prevents burning.

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