Buzz
The habit of tapping the top of a soda, beer, or any carbonated drink before opening it has been passed down through generations. While the effectiveness of this method in calming the beverage’s contents is still debated, Chris Hamlett, a chemistry lecturer at Nottingham Trent University, suggests it’s less about any magical influence and more about shifting the bubbles around.
Hamlett explored the science behind the can-tapping tradition for The Conversation, beginning with what triggers carbonation-induced foam. He explained, "The satisfying 'hiss' occurs when gas bubbles escape the liquid due to a change in the solubility of carbon dioxide (CO2)". This shift in solubility happens as a result of the pressure drop when the can is opened.
Tiny bubbles clinging to the can’s inner walls grow in size once the pressure drops (when the can is opened). As Hamlett points out, "When these bubbles become large enough, they detach from the can’s surface and rise to the top, displaced by buoyancy, and push liquid out of the way." By tapping the can, you’re essentially helping to move these gas bubbles and clear the path for the liquid, as shown in the illustration below.
Images courtesy of The Conversation // CC BY-ND 4.0
However, according to How Stuff Works, there's no guarantee that your tapping has shifted enough bubbles to calm a soda that’s been shaken. The best strategy is to let the drink settle for a while before opening it. Or, if you’re feeling bold, skip the waiting and tapping, and brace yourself for the possible results.
