This fun little experiment demonstrates what happens when you mix a base (baking soda) with an acid (lemon juice). The result is carbon dioxide which will fill up a balloon capped over the mouth of a soda bottle.
Difficulty: Easy
Time Required: 10 minutes
Here's How:
- Take the small balloon in your hands and stretch it out a bit to make it a little easier to inflate.
- Pour about 1 ounce of water into the bottom of a small soda bottle (12 ounce or 20 ounce is best).
- Add 1 teaspoon of baking soda to the water in the bottom of the bottle and stir it with a straw until it has dissolved.
- Pour in the juice of 1 lemon (about 3 tablespoons of lemon juice).
- Quickly put the mouth of the stretched balloon over the mouth of the soda bottle.
- Watch as the balloon slowly inflates.
Tips:
- If you don't have a lemon or lemon juice, you can use two ounces of white vinegar instead.
What You Need
- Small balloon
- Water
- Baking soda
- Lemon juice or a lemon
- Drinking straw
- Small soda bottle (12 ounce or 20 ounce)

