We all know that if you shake a soda-pop can before opening it that it will explode with liquid and make a big mess. My question is, why doesn’t that happen when you open the can when it comes out of a dispensing machine. You put your money in, select the soda pop you want, push the button, hear the can tumble down to bottom inside the machine, reach into the machine and receive the can. You can open the can right away and it doesn’t explode. Why not?
Note: I am from northern Ohio. We call soda pop, “pop”. I don’t want to discuss that here. Call it pop, soda, coke, what-have-you.
It sounds worse than what happens. Most of the noise is from all the cans above shifting down after the soda is released to you. It drops a couple of inches to a chute. Slides down the chute to the spot where you pick it up.
I’ve never noticed it happening with pop in cans either. But…when I buy a diet Coke in a plastic bottle from a machine, I always twist open the top very slowly to let some of the air out because it will foam up. It doesn’t shoot all over, but it will foam over the neck of the bottle sometimes.
I suspect part of it is even after shaking a can of soda it returns to its at rest state very quickly. There’s a Penn & Teller trick in one of their books where they transfer the carbonation from one can to another. You furiously shake one can then put it down and say a brief magic spell over it to transfer the explosion to the other can. Open the shaken can and it doesn’t explode. Open the unshaken can which does explode.
The only trick at work here is that with current can designs it only takes about 15 seconds for a can to “settle down” and not explode after you shake it. (The second can explodes because you squeeze it as you open it).
And that’s with a can that’s been dramatically shaken. One that simply falls probably settles in seconds.
Vending machines vary. The one in my office just pushes the cans off a kind of rack, via moving prongs, so they drop between one and two feet into the tray. The cans still don’t seem to fizz up when opened.
I agree with Big T. It doesn’t take that long for a shaken can of soda to settle down. By the time you reach down, grab it, and take it to your lunch table, the contents have settled.
The can is also cold when it first comes out of the machine. CO2 dissolves better into cold water. Increasing the temperature, even just by a few degrees, is enough to bring some of the gas out of solution once the pressure is released. But a small thump when the can is at its coldest point isn’t going to do much.
happened often enough in the past for me … about 1 outta’ 7 would have the sustained energy to ‘fizz’. i then learned to ‘snap’ the can once or twice with the fingernail of my index-finger … and the bubbles which had attached themselves to the inside wall of the can would dissipate … and there’d be no ‘fizz’. have never had one problem since.
