Wack-A-Pack balloons are self-inflating foil balloons that do not require inflation and do not have a valve. This self-inflating balloon has three components to make it inflate– citric acid, distilled water, and sodium bicarbonate (baking soda).
The citric acid and distilled water are stored together in a small pouch inside of the balloon and the baking soda is stored outside of the bag.
How to Inflate a Self-Inflating Balloon
Begin the inflation process by smacking the balloon and throwing it on the floor. You will hear a "pop" sound followed by fizzing. The fizzing noise is caused by a chemical reaction between all three elements inside the balloon.
By smacking the balloon the pouch will break and react with the baking soda creating carbon dioxide causing the foil balloon to inflate and feel colder. It will take a few minutes for the balloon to fully inflate, but when it does this balloon will remain inflated for about a week or more.
Currently, self-inflating balloons are only available in 4 inches. These balloons are also a great way for teachers to introduce chemical reactions to students in the classroom.