Science Smarts: It’s a good time to understand fire and how to put it out

By Patty Rooks on August 17, 2024.

What a hot dry summer it has been. Many parts of our province have experienced, or continue to experience dry conditions and uncontrollable fires. With there being so much in the news about the devastating fires our province has right now, I have had some questions from young scientists about how to put out a fire. I tried really hard to explain it, but for those who know me, I am much better at showing this. Of course, this is only one explanation of how we can extinguish a fire, but I hope it helps. Let’s get started!

*An adult MUST help you with this experiment as it involves fire.

Materials

– Vinegar

– Baking soda

– Beaker or measuring cup (something you can pour out of)

– Tea light candles

– Measuring spoons

– Measuring cup

– Lighter or matches

– Baking pan (to work on)

– Safety goggles

Procedure

1. Put safety goggles on.

2. Place beaker and tea light candle on the baking pan.

3. Measure 30 mL (two tablespoons) of baking soda and put it in the beaker.

4. Using the measuring cup, measure 125 mL (1/2 cup) of vinegar).

5. Pour this into the baking soda.

6. Observe.

7. Have an adult help you light the tea light candle.

8. Pick up your beaker and tip it a little bit (not enough for the liquid to come out), but just hold it there.

9. Observe.

10. What happens?

What is going on?

This is a very simple CARBON DIOXIDE fire extinguisher. You should have put the candle out once you held the beaker near the flame for a couple of seconds. Why is this? Well, when you mixed the vinegar (acetic acid) and baking soda (sodium bicarbonate), you created a chemical reaction. This chemical reaction is unstable though. It quickly decomposed into carbon dioxide and water. The bubbles released this carbon dioxide gas, and it filled the beaker. You did not see this gas because it is colourless and odourless. special gas called carbon dioxide (CO2).

This carbon dioxide takes all of the oxygen (which is needed for the fire to burn) away from the fire, allowing it to be extinguished (or put out).

Did you know that carbon dioxide is all around us. We breathe it out each time we exhale. It is useful for plants as they use it in photosynthesis. In this experiment it was also useful because it was able to put out a flame. Carbon dioxide gas is heavier than air, so as a result, it is able to put out the flame as it is poured out of your beaker and onto the flame of the candle.

Mark your calendars, the Praxis AGM is fast approaching on Wednesday, Sept. 11. We are always looking for volunteer Board members, so please consider joining us. If interested, please reach out to Patty for further details.

Patty Rooks, senior scientific consultant PRAXIS, “Connecting Science To The Community.” Contact Praxis at praxis@praxismh.ca, http://www.praxismh.ca, Tweet or follow us @PraxisMedHat, or friend us on Facebook. Address: 12 826 11th Street SE, Medicine Hat, AB, T1A 1T7 Phone: 403-527-5365, email: praxis@praxismh.ca.

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