Gilbert Gas's Balloon


To test for the presence of carbon dioxide gas in soda


  • One round nine-inch balloon (approximately)
  • One small bottle of carbonated soda
  • Teaspoon
  • Salt


Put a teaspoon of salt in the balloon. Cover the mouth of the soda bottle with the balloon. Pick up the balloon so the salt will go into the soda. Watch and observe what happens. It is a good idea to put the soda on a cookie sheet or some newspaper as this can get messy!



The salt releases carbon dioxide from the soda, making the balloon inflate. Many carbon dioxide bubbles form on each grain of salt (nucleation sites) resulting in the soda foaming up. The soda goes back down into the bottle, but the balloon stays inflated due to carbon dioxide gas.