How can the CO2 released weigh more than the gasoline I started with?

A gallon of Gasoline weighs between six and seven pounds. If you burn that gallon of gas, the carbon dioxide produced weighs about 19 pounds! How does that work?

The video below explains the chemistry and mathematics of what's going on in three minutes. An animation of the reaction helps make the chemistry easier to understand.

The presentation was created for a public presentation on the Low Carbon Diet.

The animation was created using Apple's Keynote presentation software, and then a screen capture video was made with Jing software.