Baking Soda and Vinegar Experiments: Expanding Balloon

The Expanding Balloon

After a trip to the supermarket, we've restocked our supply of vinegar and bicarbonate of soda (otherwise known as baking soda) so we're ready to do some more experimentation.

This time, we tried out the Expanding Balloon experiment.

Materials Needed the Expanding Balloon

    1 plastic bottle (e.g., a water bottle)
    1 measuring jug
    2 balloons
    2 tablespoons of baking soda
    ¾ cup of vinegar

Instructions for the Expanding Balloon

    1. Pour ¾ cup of vinegar into the empty drinking bottle.
    Expanding Balloon
    2. Make a paper funnel (or use a commercially made plastic funnel) to pour the baking soda into the balloon. We found this to be the hardest part of the experience and I had to help the boys with this a little. Perhaps it would be easier with a plastic funnel.
    Expanding Balloon

    3. Stretch the opening of the balloon over the mouth of the plastic bottle.
    Note: keep the contents of the balloon hanging over the side of the bottle.
    Expanding Balloon

    4. Engage a "count down" before lifting up the balloon and tipping the baking soda into the vinegar.
    Expanding Balloon

    5. Watch to see what happens. (The gas resulting from the chemical reaction between the soda and the vinegar should inflate the balloon).
    Expanding Balloon
    Expanding Balloon
    Hooray! It worked! Even better (according to David who had his fingers in his ears), the balloon didn't over inflate and explode!

This activity allowed the boys to engage in discussions about

  • What they predicted would happen (before we began)
  • What was happening (during the experience).

Follow Up Experimentation

Once the balloon had finished expanding, we took it off the top of the bottle and quickly tied a knot in the end of the balloon to keep it inflated.

When we let the balloon go, we noticed that it fell to the floor rather quickly. It almost seemed heavy.

We blew another balloon up (using the traditional method of blowing into it. Just as well Mum is full of 'hot air'!). Then we dropped them from the same height to test our theory that the gas in the 'baking soda' balloon was heavier than a normal inflated balloon.
Expanding Balloon

It turned out that our theory was correct. We repeated our test several times and each time the 'baking soda and vinegar' balloon fell to the floor faster than the air inflated balloon.

This was an outcome that I'd not expected. Who said that it's only children who learn through these activities?

Hmmm ... I'd better go and find out about what other experiences we can do with baking soda and vinegar! If you have any, we'd love to hear about them!

Go to other vinegar and bicarbonate of soda experiences:

Return to the Articles List for other children's learning activities.

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