Experiment | Make Your Own Fire Extinguisher

Approximate Time to Complete: 25-30 Minutes + Questions & Journal Time

Experiment Card

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About This Experiment

You’ve mixed baking soda and vinegar before, and you know it makes fizzy bubbles. Those fizzy bubbles are carbon dioxide gas. You’re going to see what happens when you pour carbon dioxide over a candle flame.

You’ll Learn:

• Fire needs oxygen to burn.
• Some gases are heavier than others.
• Heavier gases can sink down low and push lighter gases up to float above them.

Pre-Experiment Questions:

• What are the three things you need to make a fire?
• What are some different ways to put a fire out?
• What do you think is inside of a fire extinguisher?
• Will the candle flame keep burning once it’s surrounded by carbon dioxide gas instead of oxygen?

Materials

• Baking soda
• Vinegar
• Empty bottle
• Balloon
• Beaker or cup (glass)
• Candle
• Match or lighter
• Contained fireproof surface

Safety Considerations

This experiment should be performed by an adult. This experiment involves open flames. Avoid burns. Wear protective glasses and gloves. Wear fire-resistant clothing. Conduct this experiment outside or under a properly ventilated lab hood. Do not conduct this experiment near flammable substances or objects. A fire extinguisher and first aid equipment should be available and within reach. Follow all other general safety procedures. Perform this experiment at your own risk.

Procedure

Part 1

1. Light your candle.
2. Fill your beaker with air (you don’t really need to do this step, it is already full of air).
3. Pour the air in your beaker onto the candle.
4. Put the candle out by covering it with an empty glass.
   • Did anything happen?
   • Do you know what a “control” or “control group” in a science experiment is? If not, try to guess, and then look it up!

Part 2

1. Pour 2 teaspoons (10mL) of vinegar into the bottle.
2. Put 1 teaspoon (5mL) of baking soda into the balloon.
3. Put the mouth of the balloon around the mouth of the bottle, and hold it with your fingers.
4. Hold the balloon up to drop the baking soda into the bottle.
5. Once the balloon fills with gas, pinch the neck to take it off the bottle. Try not to let any gas come out!
6. Put the mouth of the balloon down into the bottom of your cup/beaker, and let the gas out.
7. Light your candle.
8. Pour the cup filled with carbon dioxide onto your candle.
   • What happened?
   • Did you break part of the fire triangle in this experiment?

Questions & Further Research

Use these questions as a guide to write a journal entry, make a poster, give a presentation, or write a research report about your experiment or a related topic.

1. Did the candle keep burning once you poured carbon dioxide over the flame?
2. Do firefighters really use carbon dioxide to put fires out?
3. When wood burns, it makes carbon dioxide, just like when you mix baking soda and vinegar. Can you explain how covering a candle works to put it out?
4. Is carbon dioxide heavier or lighter than oxygen?
5. Do you think our atmosphere has different layers of gasses like how oil, water, and honey all settle into different layers?
6. Go to the answer key to learn more about how this experiment works.