Why does coca cola explode when Mentos are dropped into it?

The eruption of Coca-Cola when Mentos are dropped into it is a result of a physical reaction between the candy's gelatin and the soda's carbon dioxide gas. When the Mentos are dropped into the soda, the gelatin acts as nucleation sites for the dissolved carbon dioxide gas to form bubbles. The sudden formation of a large number of bubbles creates a foam that rapidly expands and causes the soda to erupt.

Here is a more detailed explanation of the process:

1. Nucleation: When the Mentos are dropped into the Coca-Cola, the gelatin in the candy provides nucleation sites for the dissolved carbon dioxide gas in the soda. This means that the carbon dioxide gas bubbles can more easily form around the gelatin molecules than they can in the absence of these nucleation sites.

2. Bubble formation: As more and more carbon dioxide gas bubbles form around the gelatin molecules, they begin to coalesce and grow in size. This process continues until the bubbles become so large that they can no longer be supported by the surface tension of the soda.

3. Foam formation: The growing bubbles eventually form a foam that rapidly expands and rises to the surface of the soda. This foam is made up of a mixture of carbon dioxide gas and Coca-Cola.

4. Eruption: The rapid expansion of the foam causes the soda to erupt out of the bottle. This is because the foam displaces the soda and forces it out of the bottle.

The eruption of Coca-Cola when Mentos are dropped into it is a fun and harmless experiment that demonstrates the power of nucleation in creating bubbles.