Why is pop in Mentos a chemical change?

When Mentos are dropped into a bottle of soda, a chemical reaction takes place between the gelatin in the Mentos and the aspartame in the soda. This reaction produces carbon dioxide gas, which is what causes the soda to fizz and foam. The chemical change that takes place can be represented by the following equation:

C6H12O6 (aspartame) + C6H12O6 (gelatin) -> 2CO2 (carbon dioxide) + 2H2O (water)

The products of this reaction are carbon dioxide gas and water. Carbon dioxide gas is what causes the soda to fizz and foam, while water is simply released into the soda.