Dry Ice Balloon

Dry ice balloon is another easy way to show an example of how density works.  Here is what you will need:

  • Balloons
  • Dry ice (if you need access contact our group)
  • A small bottle that a balloon can fit over
  • Water

For the actual demo,  you will blow one balloon up manually.  This balloon can just be filled with air.  The second balloon will be filled with vapor from dry ice (carbon dioxide).  You should place 1-2 pellets of dry ice in a small beaker/jar and add water.  Once the vapor starts to form, place the balloon over the bottle opening and let it fill up.  If the reaction starts to slow down, gently shake the bottle.  Once the balloon is full, remove it and tie off the end.  Now, drop both balloons from the same height.  You will notice one falls faster than the other.  This is because the dry ice balloon is filled with 100% carbon dioxide, which is heavier than exhaled air that fills the other balloon (exhaled air does contain carbon dioxide, however at a smaller percentage than the balloon filled with dry ice vapor).  This makes the balloon filled with CO2 denser than its air counterpart.  By being denser, the CO2 balloon is less buoyant than the air-filled balloon.  Thus, the CO2 balloon drops faster, similar to dropping a cork and a stone into a pool.