DIY CO2 Extinguisher

A carbon dioxide fire extinguisher puts out a flame using carbon dioxide gas produced from a chemical reaction. Mixing household baking soda and vinegar releases carbon dioxide gas, which is heavier than normal air and quickly extinguishes a fire.

Materials needed

• Baking soda from the kitchen
• Vinegar
• Two small cups, such as a blue cup and a pink cup
• A candle
• A lighter to light the candle flame

The chemical reaction

The experiment begins by placing some baking soda into a cup and lighting the candle with a lighter. When vinegar is poured onto the baking soda, the two substances mix and trigger an immediate chemical reaction. This chemical reaction releases carbon dioxide gas into the space above it. The rising carbon dioxide gas is then captured inside an empty cup held over the reaction.

Extinguishing the flame

Once the cup collects the carbon dioxide gas, it is tilted over the burning candle flame as if pouring liquid. As soon as the gas pours out over the candle, the flame goes out. Carbon dioxide gas has more weight than the air surrounding the flame. Because it is heavier than the surrounding air, the carbon dioxide settles over the flame and easily puts it out. This ability of carbon dioxide to put out fire has also been used to extinguish large fires during major fire accidents.

Comparing the weight of gases

When looking at two cups, such as a blue cup and a pink cup, they appear to be completely empty and equally light. However, if one cup contains ordinary air and the other cup holds carbon dioxide gas, their weights are not the same. The cup filled with carbon dioxide has more weight than the cup filled with regular air. Because fire is used to test this effect, the activity must always be carried out with the support of parents to remain safe.