Re: Is it possible to shake a can of soda so much that it will combust?

Hi Charissa,

I have never actually done the experiment myself, though I'm told by 
someone who has that if you shake a warm can of soda, you can get the can 
to expand fairly easily.  Shaking the warm can of soda causes carbon 
dioxide that's dissolved in the soda to exsolve (come out of solution), 
which causes the can to expand.  This expansion disrupts the integrity of 
the can so that it's more susceptible to damage when shaken.  In other 
words, the expansion causes the walls of the can to get thinner.  The basis 
of this idea is that as you increase temperature, more carbon dioxide gas 
will exsolve from solution.  The increased gas concentration in the area 
between the soda and the can causes expansion to occur.  Simply shaking a 
cooled can of soda will not expand the can to the same degree as if the 
soda is warm.  Likewise, heating the soda in the can enough could possibly 
cause the can to burst.  I'd imagine that the cans are designed to be able 
to withstand a fair amount of shaking under typical temperatures.  A glass 
container is too thick for the same amount of expansion to occur.

Henry's law explains this concept more formally.  Henry's law states that 
gas solubility depends on pressure, temperature, the gas, and the solvent.  
You can also think of this concept the other way: when you open a cold 
bottle of soda, you release pressure on the soda in the bottle and cause 
the temperature of the soda to decrease.  Sometimes you can actually find 
bits of ice at the top after opening a bottle of soda.  (I have also heard 
that if you shake up a can of soda enough, you can get all of the soda to 
foam out of the can when you open it.)

I hope that this explanation helps you.

Sarah Earley
CU Boulder