🚀 go-pugleaf

In article <1993Jan20.200301.10512@magnus.acs.ohio-state.edu>, 
ceubanks@magnus.acs.ohio-state.edu (Charles F Eubanks) writes:
 
> In article <mcampbel.727553725@eola.cs.ucf.edu> mcampbel@cs.ucf.edu (Mike 
Campbell ) writes:
> >judson@watserv.ucr.edu (Mike Judson) writes:
> >
> >>Does tapping the top of soft drink cans really prevent them from 
> >>"exploding" when you open them, or is it a UL?
> >
> >I think this is pure poppycock.

[description of experiment deleted]

> Try the experiment again, but this time, immediately after shaking, grip the
> can firmly and smack the top VERY sharply with your knuckles and open it
> right away.
> 
> I beleive you will see a significant reduction in the amount of spewing and
> foaming compared to an un-smacked can opened at the same time.  One theory
> developed during a fast and loose discussion on the subject is that the
> can top flexes downward, sending a shock wave (of sorts) through the
> excessivly pressurized gas in the can created by bringing CO2 out of
> solution by shaking.  The shock wave temporarily sends the CO2 back into
> solution and thus reducing the total pressure in the gas.
> 
> Inviting all other theories, thoughts, musings, flames..... ;)

OK, you asked.  I think it is legend, but to the extend that it does work, I 
don't think it would be because of CO2 going back into solution.  The time is 
probably too short and the surface area for absorption too small.

Rather, I would expect that a foam would form on top of the liquid in the yet 
unopened can after it is shaken.  A sharp tap would cause the bubbles to 
break or coalesce.  There would be less liquid surrounding these fewer, but 
larger bubbles.  When the can is opened, the rapidly escaping gas would carry 
less liquid along with it and thus reduce the spewing.

Phil

-----
Philip L. Gravel                           Internet: pgravel@nap.amoco.com
Amoco Chemical Company, Chicago, IL        Phone:    (312)856-3553
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These opinions aren't worth the paper they're written on and
certainly don't reflect those of my employer.