How to Conduct a Water Expansion Experiment Using Water Balloons

Make a splash with a water balloon project.

Besides a volcano that loudly spews red gelatin, no science experiment may be more fun for kids than a water expansion project with balloons. All the kid-friendly elements are present: water, balloons and sense of wonder about what will happen next. A few of these projects involve heat, so adult supervision for elementary school students is mandatory. Watch as students have fun with water and balloons while learning important lessons about air pressure, chemistry and physics.

Things You'll Need

• Balloons
• Vases or platforms
• Extended-reach lighter
• Glass jar (such as a marinara jar)
• Dish soap or Vaseline
• 4-inch squares of newspaper
• Sugar
• Bowl
• Packet of active dry yeast
• 1-liter bottle

Instructions

Balloon Under Pressure

1. Inflate one balloon, knot it and set it aside.

2. Pour ¼ cup of water into a balloon, knot it and set it aside.

3. Hold the lighter under the balloon filled only with air. It should pop rather quickly.

4. Hold the lighter under the balloon with water. Keep the lighter there and watch the balloon very slowly expand but not break. The water is absorbing the heat from the flame so that the rubber does not become hot enough to break. The water – like water on a stove – takes a while to heat up.

5. Turn off the lighter and watch the balloon decompress because when water cools, it releases heat.

Balloon Defies Physics

1. Lubricate the mouth of a jar with dish soap or Vaseline.

2. Fill a balloon with water so that it is slightly larger than the opening of the jar. It should still be elastic enough to manipulate in shape.

3. Ask children to push the balloon into the jar. They won’t be able to – until you show them a method of expansion.

4. Light two pieces of newsprint and drop them into the jar.

5. Cover the opening of the jar with the water-filled balloon. Hold it gently by the knotted end and watch as the balloon begins to bounce as the heated air inside the jar begins to expand and contract.

6. 

   If you can find them, balloons of different shapes could affect the outcome of your project.

   Watch the kids watching in wonder as a vacuum pulls the balloon into the jar. (Remove the balloon by either popping it or gently inserting a straw into the jar and using it as a shoehorn to lift the balloon out.)

Yeast of All Balloons

1. Stretch out a balloon thoroughly by pulling it in several directions. Then set it aside.

2. Mix 1 cup of hot water and 2 tbsp. of sugar in a bowl. Add the yeast packet and stir again.

3. Pour the mixture into a 1-liter bottle.

4. Wet the balloon with water, then place it over the mouth of the bottle.

5. Watch in amazement as the balloon inflates and eventually stands upright on top of the bottle. The yeast, feeding on the sugar, produces carbon dioxide and fills the balloon with gas. The same chemistry concept explains why yeast is a key ingredient in making bread rise.

Tips & Warnings

• As a variation to the last project, substitute baking powder for the yeast and do not add the sugar. Test to see which leavening agent takes longer to inflate the balloon.

References

• Science Fun.org: The Fireproof Balloon
• Balloon in a Bottle: An Air Pressure Experiment
• Balloon in a Bottle
• Exploratorium.edu: Yeast Air Balloons

Resources

• Super Science Fair Projects.com: A Water Balloon Science Fair Project
• Science Buddies.org: Balloon Morphing: How Gases Contract and Expand