Place the neck of the funnel into the neck of the glass bottle. Pour 6 ounces of vinegar into the bottle. Remove the funnel and rinse and dry it.
Stretch the balloon to make it easier to inflate. Place the neck of the funnel into the neck of the balloon. Pour in 1 teaspoon of baking soda.
Remove the funnel from the neck of the balloon. With the bottom of the balloon toward the floor, bend the neck of the balloon over and stretch it over the neck of the bottle. Do not let baking soda fall into the bottle. Keep the part of the balloon with the baking soda bent and hanging over the side of the bottle.
Pull the balloon straight up over the bottle and allow the baking soda to pour into the bottle. Swish the contents of the bottle a few times to mix the vinegar and baking soda. The chemical reaction between the 5 percent acetic acid vinegar and the alkaline baking soda releases carbon dioxide that inflates the balloon.
Twist the neck of the balloon several times and hold it closed. Pull the balloon off the neck of the bottle. Knot the balloon.
Experiment with other balloons by varying the amount and proportion of vinegar and baking soda. Usually, the more active ingredients you use, the larger the balloon will inflate. Record your data.
Put a votive candle into each jar. Light the votive candles with the help or supervision of an adult.
Release the gas from one of the balloons into one of the jars carefully to avoid the force of the gas extinguishing the votive candle. Observe the two jars. Carbon dioxide, the gas produced inside the balloon by the chemical reaction of the vinegar and baking soda, is heavier than air. It sinks to the bottom of the jar and pushes the oxygen out of the jar. Since fire needs oxygen to burn, the flame is extinguished by the carbon dioxide. The other candle continues to burn because it has a plentiful supply of air.