Heres What You Will Need;

Balloon, backing soda, vinegar, and a bottle.

Step 1: First Step.

Take the balloon and fill it up with baking soda fill about half the balloon.

Step 2: Next.

Put vinegar about half way full in the bottle.

Step 3: Following.

Put the balloon over the lid of the water bottle and let the baking soda drop into the bottle.

Step 4: Lastly.

Watch the balloon fill up with co2.