Activity time: 7 minutes

Materials for Activity

• Tray to hold experiment materials
• One- or two-liter bottles, one bottle for each group
• Balloons that will fit over tops of the bottles, one per group
• Vinegar
• Baking soda
• Two 1/4 cup measuring cups
• Funnel (can be made from a sheet of paper) or eyedropper
• Optional: Two additional trays for materials, if using Station Model
• Optional: Written instructions, if using Station Model

Preparation for Activity

• Gather materials.
• Review directions.
• Prepare tray(s) with materials for experiment.
• Optional: If participants will rotate from experiment station to experiment station in groups (Station Model), print or write the instructions for this experiment and set at this station.

Description of Activity

Give these instructions while a co-leader or volunteer performs this experiment:

In this experiment, carbon dioxide blows up a balloon. Gather a small jar or container, a balloon, 1/4 cup of baking soda, an eyedropper or funnel, and 1/4 cup of vinegar. Pour the baking soda carefully into the bottom of the container. Next, use a funnel or eyedropper to pour the vinegar into the balloon. Carefully making sure the vinegar stays in the balloon, fit the end of the balloon tightly over the jar. Now, for the miracle—cautiously, tip the balloon up so the vinegar and baking soda mix, and watch what happens to the balloon!

Note: The procedure for this experiment is relatively simple, but the trick is to make sure the balloon fully covers the jar opening so that the carbon dioxide is trapped when it is created.

What did Priestley realize from this experiment? Chemical opposites react in this experiment: An acid (vinegar) reacts with a base (baking soda) and creates several byproducts. One of the byproducts is the gas, carbon dioxide. Carbon dioxide is heavier than oxygen, so it sinks to the bottom of the bottle, forcing the oxygen-rich air up and into the balloon and causing the balloon to expand.