To: pinhole@exploratorium.edu
Subject: "four words...." <patagium@earthlink.net>: Re: Co2 Gas?
From: "Daniel R. Defoe" <djdefoe@juno.com>
Date: Fri, 29 Jan 1999 22:51:58 EST
Dan
As i understand it..., the raisins and various other objects (i
have
used "unpopped" popcorn also) have little "nicks" and "crannies" (don't
know what they are..., but they're not crannberries!) distributed around
the surface. When dropped into a glass of tonic water, these little
"nicks" have tiny tiny tiny air bubbles trapped in them... I would
suppose being close to room temperature (the raisins that is...) also
aids the process of CO2 gas collecting at the various air bubbles on the
surface of the raisins. Sometime during my lessons at the Exploratorium,
i recall that tiny tiny water droplets need condensation nuclei to form
(see "Cloud in a bottle" snack write-up), also...boiling water appears
to have bubbles originating from certain areas (little tiny "nicks"
again?!)...and didn't chem. class have "boiling chips"... in other
words, these processes have a certain threshold in order to occur and
the presence of these tiny tiny "nicks" or "condensation nuclei" speed
the process along... (Wonder if this is related to seeding clouds at
all?! or... when you drop some salt into a glass of beer?! But who would
do that?!)
Anyway, as the CO2 collects on the raisins the density of the
"raisin/CO2/air bubble" decreases and eventually becomes less than the
density of the tonic water and begins to float up... when it reaches the
surface, the gases escape to the air and the raisin's density is more
than the tonic water again and sinks back down... then we start the
cycle again....*smile* As PD (Paul Doherty) would say...: "it's more
complicated than that..." *grin* He once gave me an article that
mentioned the terminal velocity of the bubbles floating up to the
surface... It was from a book called _Bubbles (?!) in a glass of beer_,
the Exploratorium library probably has a copy of it...
blue skies,
tien
ps. it's kinda early...so forgive me if i answered the wrong question!
:o)
Tien Huynh-Dinh
The Accelerated School
116 Martin L. King Blvd
Los Angeles, Calif. 90011
Yes, I agree-but take note: it works with smooth objects (i.e.grape)
too...but prob same principle applies and co2 released at the
surface.....Dan
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