I have a problem with Diet Pepsi.  When I buy it in the 24 fl oz
bottle, in a Super 6 pack, I invariably have a few of them (really
almost all of them), that when opened resemble a pepsi volcano.  Soda
goes everywhere.  Is there a way to keep this from happening?  What is
the cause?  The approach I've taken in the past is to SLOWLY turn the
lid, tightening it back up when the bubbles get too high.  The problem
is this takes as much as 30 MINS!  I should also tell you I live at
7000+ ft elevation (Colorado Springs).  Please help.

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Request for Question Clarification by revbrenda1st-ga on 26 Feb 2003 13:32 PST

Hi Mrtrivia,

I've just sent an e-mail off to the Colorado Soft Drink Association.
Perhaps I'll get the answer and/or a solution to your problem soon.

Regards,
revbrenda1st

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Request for Question Clarification by revbrenda1st-ga on 26 Feb 2003 18:02 PST

Hi Mrtrivia,

I did indeed receive a reply, but it contained no answer or solution.
I'm sorry. Perhaps a more scientific approach by a suitable researcher
will help.
I was wondering, though. Do any others in you family or group of
acquaintances there have a similar experience with the fizzing?

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Request for Question Clarification by feilong-ga on 26 Feb 2003 19:22 PST

Hi Mrtrivia,

Is the softdrink cold enough when you open it? Perhaps it's just bottle cold.

-Feilong

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Request for Question Clarification by pinkfreud-ga on 26 Feb 2003 19:37 PST

Do you have this problem only with Diet Pepsi in the 24-ounce bottles,
or do other sodas behave similarly?

The problem is definitely your elevation.  At sea level, we experience
14.7 pounds per square inch.  At 7000+ feet, that drops to less than
11.34 PSI.(1).  That means that there is 30% more atmospheric pressure
at sea level than there is where you live.  Your Diet Pepsi was
probably bottled close to sea level.  So while it may have been closer
to equilibrium there, when you take it to your elevation, the pressure
inside the bottle is considerably greater than the pressure outside
the bottle.  When you open the bottle, all of that pressure is
released rather violently (the volcano effect).

Now to keep it from happening, you have to minimize the pressure
inside the bottle as much as possible.  So the physics behind it is
that Pressure times Volume divided by Temperature is a constant.  So
if you want to reduce the pressure, you either need to increase the
Volume or decrease the Temperature.  Well, the only way to increase
the volume is to open the bottle, and we know what happens when you do
that, so reducing the temperature is your best bet.  Get them as cold
as possible before you open them.

Also, and I'm sure you've already tried this one, make sure that you
agitate the bottles as little as possible before attempting to open
it.  That problem occurs at sea level also.

I hope this helps.  If anything you can switch to two liters or maybe
try cans and see if that works out any better.



(1) http://www.pumpworld.com/atmos.htm

This seems to be the solution, but I will say if you let the bottle
get TOO cold, and the pepsi freezes, you get a much worse reaction as
the pepsi is brought back to room temperature.  Namely, big chunks of
pepsi ice get shot out of the bottle.  I don't normally like my
pepsi's cold, but I guess if its that or 30% less pepsi, I'll just
live with it.  Thanks for the research.  Interstingly, a co-worker
drinks diet coke in the same kind of bottles, and does not experience
this problem...perhaps coke has a bottling plant in CO.

This doesn't answer the question, but it's interesting:

http://math.ucr.edu/home/baez/physics/General/fizziks.html