Praxis: Fireproof balloons

By Medicine Hat News on August 25, 2018.

Well, the time has come, and someone has to say it: It is back to school time! Oh my am I excited to begin a fresh new school year. One of the things that I love to share with all of my colleagues at this time are some exciting back to school experiments. I think it is important these experiments get the students thinking and as excited about science as I am. Here is one that you can do at home as well. Let’s get started!

*Remember to ask an adult before doing this experiment.

Materials

– barbecue lighter

– balloons

– funnel

– water

– measuring cup

– measuring spoons

– chair

– lots of hot air

– science helper

Procedure

1. Fill one balloon with just air. Tie and set aside.

2. Measure and fill the second balloon with about 1/4 cup (125 mL) of tap water. Blow the balloon up entirely and tie it. Set aside for a minute.

3. Have a science volunteer come and sit in the chair.

4. Ask the volunteer what they think may happen if you were to place the flame from the barbecue lighter under the balloon without water.

5. Have an adult touch the flame from the barbecue lighter to the bottom of the balloon.

6. What happens?

7. Now, ask the volunteer what they think will happen with the second balloon.

8. If they are confident in their response, ask if you can hold it over their head as you hold the barbecue lighter to the bottom of the balloon!

9. Hold the flame to the bottom of the balloon where you can clearly see the water.

10. What happens?

What is going on?

Balloons and a flame are clearly not something you think should go together! As you saw with the first balloon, it popped almost as quickly as you held the flame to the balloon. But with the second balloon, it should not have popped. You actually should be able to hold the flame there for quite some time and it will not pop! Note: this is as long as you keep the flame under the water in the balloon.

We all know to keep balloons away from sharp object and open flames as they are extremely fragile. When the water is placed inside the balloon though, it allows for most of the heat from the flame to be absorbed into the water. This in turn allows for the rubber to not absorb as much heat and as a result not weakening the rubber and allowing the balloon to not pop.

Water is an excellent absorber of heat. It takes a great deal of heat to change the temperature of the water. This is why it takes so long for a kettle to boil. On the other hand, when water cools, it releases a great deal of heat.

Patty Rooks is senior scientific consultant at 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.

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