What causes the explosion when Mentos are dropped into Diet Coke?
Carbonated beverages have carbon dioxide (CO2) in them. If you shake a can of Coke vigorously before you open it, the effect is similar to dropping Mentos in: the Coke shoots out in a narrow stream. In contrast, if you open an unshaken can of Coke, the CO2 will leave gradually and quietly, and is easier to drink; the release of bubbles is so slow that it will be hours before the soda turns “flat.” The CO2 is dissolved in the Coke under pressure. Gases, including CO2, can dissolve into liquids much like sugar or salt can. But the amount of gas that will dissolve into a liquid depends on the pressure that the gas and liquid are under. At atmospheric pressure (about 15 psi), only a small amount of CO2 will dissolve into Coke. If you want more gas to dissolve, then you have to increase the pressure of the CO2 until it is, say, two or three times atmospheric pressure. That’s why soda cans have to remain sealed: they contain CO2 under pressure. When you open the Coke container, the pressure
