Why does dropping a Mentos into a bottle of soda create a reaction?
The reaction occurs because of a simple rule of physics. It is not a chemical reaction. Soda drinks contain a certain amount of CO2 (carbon dioxide) dissolved in water in the form of tiny bubbles. This combination of water and CO2 molecules is in a permanent instable state. When Mentos dragées fall into this liquid, this state is disturbed. The more Mentos are dropped into the liquid the more this state is aggravated. The reason for this lies in the surface of a Mentos which looks smooth but is actually very rough! Within the nooks and crannies of the microscopic rough surface, bubbles form, which are in turn transformed into foam, which can lead to very impressive foam fountains.
