100 Days Project

Nanogirl: Star Science

Nanogirl wants to find 100 friends to do science experiments with her to prove that no matter who you are or what your education level, you can always have fun with science.

Day 26:

9 year old Katie blows up a balloon with cola and salt!

We have already seen how to blow up a balloon on a bottle using baking soda and vinegar, but I've never seen this experiment before.  Katie who is 9 took a balloon and filled it with a spoonfull of salt.  She then carefully placed the balloon over the bottle top and lifted it so the salt fell into the cola bottle.  It immediately started to bubble and the balloon inflated in front of our eyes!  When the reaction was finished, we carefully removed the balloon and tied it closed, but when we threw it we found it was a reall heavy balloon compared to one we blew up normally with our mouths, showing that the gas inside it was much more dense.

So what happens when you add salt to cola?

Cola is full of dissolved carbon dioxide - that's what makes it fizzy.  The salt grains acts as nucleation sites for this disolved carbon dioxide and provide enough energy for the gas to form bubbles.  The salt also dissolves into the cola which causes the pH to change resulting in a decrease in the solubility of the carbon dioxide in the cola.  This then releases the carbon dioxide as a gas and also creates bubbles.  So the two things combined are why its such a frantic reaction.