Eli5: Why does beer do that thing when hit with another beer on its cap

Question

Eli5: Why does beer do that thing when hit with another beer on its cap

In: Chemistry

Answer 1

Beer is carbonated, that means it has CO2 gas dissolved in the liquid. Generally there is more gas dissolved then there wants to be based on the pressure of the air on top of the beer. When you tap someone’s bottle you send a pressure wave thru the beer in their bottle. This wave bounces around the bottle reflecting off the glass and in some points the pressure will be lower than normal so the CO2 escapes the liquid and makes a bubble.