how does a shaken can of soda lose its pressure over time, if its sealed?
In: Chemistry
Containers aren’t perfectly sealed. The gas will slowly escape through pores in the container over time. This is actually used intentionally in several industries. Hydrogen, for example, is a notoriously hard gas to store, because it’s very good at simply passing through any container you store it in to escape. Seeing this escape rate change can tell us that there is a breach of some sort in the container, which is very helpful in pipelines and sealed circulation systems. This gas escaping happens all the time, even without shaking the bottle. But for the purposes of a bottle of soda, for example, this takes months or years to occur and notably make the drink go “flat” even before opening it.
To everyone talking about pressure increasing when you shake a bottle, [that is definitely not true](https://youtu.be/K-Fc08X56R0?t=40s) and what you’re instead thinking of for that foaming is nucleation sites created when you shake the bottle. You can hit the side of a bottle after shaking it to disrupt the nucleation sites attached to the edge of the bottle to let them re-settle at the top of the liquid, minimizing that foamy explosion.
So here’s the thing: it doesn’t.
The can has exactly the same pressure inside whether you shake it or not.
When you shake it though you create a bunch of bubbles. The bubbles you create in jostling the soda allow more of the gasses to escape. The more the gas can patch onto things, the more escapes at once. That’s why dropping mentos into soda makes it explode, because the gasses are latching onto the rough surface of the candies
The reason it doesn’t explode after you shake it and leave it back alone is because all the little bubbles inside the can eventually pop. You can even help that process along by tapping the sides and top of the can after it’s shook.
The CO2 is dissolved in the liquid because it’s under pressure. They CO2 leaves the liquid in the form of bubbles usually slowly. When you shake a soda, you’re creating tons of tiny bubbles that the co2 can escape from (like the foam heads after pouring) causing a huge burst of gas if opened right away. However, if you leave that shaken soda alone for a while, the CO2 released isnt escaping from the can, but dissolving back into the liquid.
Then pressure is still the same. The difference is whether or not the CO2 is dissolved in the liquid or not.
Because when you shake the can, it gets angry little bubbles mixed in the soda that cling to the inside wall of the can. They’re so mad because they’re under so much pressure and have a lot to deal with, and you’re just making it worse for them. Over time, they calm down though, and instead of being disturbed inside the liquid, they let go. The angry bubbles float up to the top of the can, and are no longer mixed inside the liquid. When you open the can, since there isn’t any soda in the way now, you just get a burst of gas.
For a fun experiment at home, shake up a can of soda real good. If you opened it now, you’d paint the room with soda and make your parents mad. BUT, before you open it, flick the sides of the can all around, as hard as you can. Snap your fingers and then pop the top! Guess what, no mess! Impress your parents and show them the cool science you learned on the internet!
Or, put another way, how does shaking a can of soda increase its pressure, if it’s sealed ???
As far as I know, shaking a can releases the diluted gas in the soda and increases the pressure in the can. after a while, a considerable amount of the gas released the most returns to connect with the molecules of the liquid.
I don’t know how the molecules interact exactly, but I believe this are the start of the answer you’re looking for
Latest Answers