eli5 – why does tapping the top of a pop can make it fizz less? Or is that just a myth I’ve been practicing for 30+ years?

Question

What the title says. Pop means soda btw.

In: 1560

Answer 1

It’s not a myth, and it actually works best when you tap the sides! When a soda is shaken, lots of tiny air bubbles are formed by the tiny bit of air in the top of the can. These bubbles serve as nucleation sites for the CO2 to come out of solution from being dissolved in the soda. These nucleation points make the CO2 come out of solution far, far faster than it would otherwise be able to do! When you tap the sides of the can, you dislodge the air bubbles and the float to the top and pop, so they can’t help the CO2 come out.

Nucleation sites are important for many chemical and physical reactions, including raindrops forming, water boiling, and crystal formation. All require a nucleation site in order to happen!

Edit: So, I did some digging after posting my comment, and [this video](https://youtu.be/r6tLeYJQS58) seems to indicate that tapping itself has no effect, but the time delay from the tapping is what does the trick.