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This one seems to cause some very negative comments.



 
 
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  #11  
Old January 21st 05, 08:17 PM
Ross Vandegrift
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On 2005-01-21, spiral_72 wrote:
Ignoring the air present in the container when it was sealed, and
introducing 1 Kg (2.2lbs) of dry ice in my 6.813 L tank, while the air
in my living room is 24 C (75 F)
final pressure inside the tank will be 8238.7 psi.

Oh, crap.


Well, the problem I can think of, even if you put less in:

CO2 is heavier than air. So if the pressure isn't high enough,
it'll just sit in your bottle and not do anything fun or interesting.

On the other hand, that strikes me as a better idea than winning a
Darwin award, as one poster suggested... ::-)


--
Ross Vandegrift

"The good Christian should beware of mathematicians, and all those who
make empty prophecies. The danger already exists that the mathematicians
have made a covenant with the devil to darken the spirit and to confine
man in the bonds of Hell."
--St. Augustine, De Genesi ad Litteram, Book II, xviii, 37


  #12  
Old January 21st 05, 08:34 PM
spiral_72
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HA, ha...... go ahead and laugh, Ye' of little faith.

My idea just may revolutionize the aquarium hobby as we know it. Quite
possibly the WORLD!

Anyways....... I bought some dry ice at Publix (a grocery store) for
$1.09 a pound.... Cheap enough I guess. I put about 1 inch of water in
a 20oz coke bottle and 3 pieces of dry ice about the size of a quarter
I suppose......Screwed the top on and um, hehe It went from a coke
bottle shape.... to a um, round kinda shape and all the pleats in the
bottle pulled out.......That is untill it exploded.

So, cool I know it works..... Guess I'll start out small and monitor it
with a pressure gauge.

Oh, yea....... Kids, Don't try that at home......... And if you do.....
leave me a message and tell me that wasn't the most excitement you've
had since breakfast.

  #13  
Old January 21st 05, 09:46 PM
Richard Sexton
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In article .com,
spiral_72 wrote:
Anyways....... I bought some dry ice at Publix (a grocery store) for
$1.09 a pound.... Cheap enough I guess. I put about 1 inch of water in
a 20oz coke bottle and 3 pieces of dry ice about the size of a quarter
I suppose......Screwed the top on and um, hehe It went from a coke
bottle shape.... to a um, round kinda shape and all the pleats in the
bottle pulled out.......That is untill it exploded.


Hey if you like that you should try to find the webpage
that has the videos of a guy dropping one pound blcoks
of pure sodium metal into water. That makes a nice bang too
with the added benefit of throwing molten metal and
lye all over the place.

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  #14  
Old January 22nd 05, 12:24 AM
Pete
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(Richard Sexton) wrote in :

In article .com,
spiral_72 wrote:
Anyways....... I bought some dry ice at Publix (a grocery store) for
$1.09 a pound.... Cheap enough I guess. I put about 1 inch of water in
a 20oz coke bottle and 3 pieces of dry ice about the size of a quarter
I suppose......Screwed the top on and um, hehe It went from a coke
bottle shape.... to a um, round kinda shape and all the pleats in the
bottle pulled out.......That is untill it exploded.


Hey if you like that you should try to find the webpage
that has the videos of a guy dropping one pound blcoks
of pure sodium metal into water. That makes a nice bang too
with the added benefit of throwing molten metal and
lye all over the place.


There's one around!??!! Oh man I remember wishing that ever since high
school chemistry class. Our teacher has this huge chunk of sodium (kept
in oil) and he only gave us a tiny chunk to put into a beaker of water
to watch the reaction. I always wanted to get my hands on that chunk
and put it in a swimming pool... or how about a bucket of chlorine. If
sodium reacts that well with H2O I'm sure it would be dandy with CL for
a quick reaction to NACL :P


Actually spiral, I might have a safe (if less exciting) way for your
idea to work. Since all you want to do is have a consistant amount of
CO2 going into your tank, you need a reactor that is consistant but
doesn't build up pressure.

If you have an open bottomed box submerged in your tank with an air hose
from it to your CO2 tank (no valve), the amount of CO2 going into your
tank would depend on the size of the box (the surface area of the open
side). Excess CO2 produced would eventually overflow the box and bubble
up so no explosion risk.

If you find you're not getting enough CO2 dissolving into your tank
water, just get a bigger box which will have a bigger surface area for
the CO2 to react and dissolve into the water. I believe putting it
deeper also works.

Once you have the right size and getting 20-30 ppm of CO2 in your tank,
if you find you're wasting too much CO2 (it's bubbling out of the box)
just insulate the CO2 container more to slow it down.. you should be
able to get a pretty close balance so little CO2 is wasted.

Only problem with this method would be if the CO2 sublimates so quickly,
even with insulation that you waste too much of it.


All that being said, it might be easier and cheaper (unless you get some
free dryice) to go the yeast/sugar DIY co2 method which also has been
known to blow up bottles if that's a must :P

Cheers
P.
  #15  
Old January 22nd 05, 01:21 AM
Dan White
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"Pete" wrote in message
...
"Dan White" wrote in
:

"Pete" wrote in message
...
"Dan White" wrote in news:0t%Hd.571$vo6.564
@fe11.lga:

"spiral_72" wrote in

news:1106256969.936458.265300

3. If you rely on the speed of it melting to dictate the injection
rate


Just a nitpick, but CO2 sublimes instead of melts.

dwhite




ROTFLMAO. Oh man I know, I'm a science geek I do that nitpicking
stuff myself. I just didn't think it was worth it having people look
up the definition of sublimation :P

P.


Like they say, "Damned if you do, damned if you don't."

dwhite



Hey, just thought of something. CO2 in a pressured tank is in liquid form.
So if he puts this dry ice in a sealed tank that does get a high enough
pressure once enough CO2 has sublimated, as the rest of the CO2 thaws it
will turn into a liquid instead of a gas... so it would 'melt'. hehe.


Hmmm, well I'm not so sure it would work quite like that, but maybe! Vapor
pressure diagrams were a long time ago.

dwhite


  #16  
Old January 22nd 05, 01:32 AM
Dan White
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"spiral_72" wrote in message
oups.com...
Well, if I figured this right:

P = n * R * T / V Whe

P = pressure in atm
n = amount of substance in moles
R = Thermal expansion ( 1atm / K*mol )
T = Temp change in Kelvins
V = Volume of a sealed container in Liters

( n ) for CO2 is 22.727mol
( R ) for CO2 is 0.08206
( T ) is 298K
( V ) is 6.81322 Liters

Ignoring the air present in the container when it was sealed, and
introducing 1 Kg (2.2lbs) of dry ice in my 6.813 L tank, while the air
in my living room is 24 C (75 F)
final pressure inside the tank will be 8238.7 psi.

Oh, crap.


I get about 1200 psi. Your formula gives you about 81 atm. 1 atm = 14.7
psi.

You should be fine if you go with 1" thick steel.

dwhite


  #17  
Old January 22nd 05, 07:13 AM
Elaine T
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spiral_72 wrote:
HA, ha...... go ahead and laugh, Ye' of little faith.

My idea just may revolutionize the aquarium hobby as we know it. Quite
possibly the WORLD!

Anyways....... I bought some dry ice at Publix (a grocery store) for
$1.09 a pound.... Cheap enough I guess. I put about 1 inch of water in
a 20oz coke bottle and 3 pieces of dry ice about the size of a quarter
I suppose......Screwed the top on and um, hehe It went from a coke
bottle shape.... to a um, round kinda shape and all the pleats in the
bottle pulled out.......That is untill it exploded.

So, cool I know it works..... Guess I'll start out small and monitor it
with a pressure gauge.

Oh, yea....... Kids, Don't try that at home......... And if you do.....
leave me a message and tell me that wasn't the most excitement you've
had since breakfast.

Heh. You haven't been around a biology lab enough. We used to take dry
ice pellets and put them in latex gloves. Tie the end in a knot and
stick the glove over by someone. It eventually blows up into a balloon,
and pops. *bang* Everyone jumps.

Juvenile, but hey - graduate school brings out the best in everyone. ;-)

--
__ Elaine T __
__' http://eethomp.com/fish.html '__

  #18  
Old January 23rd 05, 01:08 AM
spiral_72
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Hey, you know what? You are right..... I went back and checked my
little engineer's book........ 1atm=14.7psi.......not 101.3psi
Thank you. If nothing else it makes me feel better about my tank

  #19  
Old January 23rd 05, 02:05 AM
Dan White
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"spiral_72" wrote in message
oups.com...
Hey, you know what? You are right..... I went back and checked my
little engineer's book........ 1atm=14.7psi.......not 101.3psi
Thank you. If nothing else it makes me feel better about my tank


Sure. You gonna give it a try?

dwhite


  #20  
Old January 23rd 05, 06:37 PM
Morten
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"spiral_72" wrote in message
oups.com...
Alright, I've got this idea. Boy, that sounds like the beginning to an
end.

I figure I can drop dry ice in a tank, cap it with a regulator and have
CO2 for some period of time for my planted aquarium. Obviously it will
require more than a handful of dry ice and chances are it ain't quite
that simple. Right now I am building a tank with a mouth wide enough to
accept an entire piece. I figger I'll pack the stuff in there like the
old shotgun wadding with a length of 2x2 or something until it's full,
and cap it.

I run a search on this over the web and the Google groups. I got the
same response: "DON'T DO IT, IT'S TOO COMPLICATED"

What's up with dat? Any particular reason? I don't want to hear that
the stuff is not sanitary either. The air in my house probly ain't
sanitary after a nice homemade bowl of chille. Heck, it's free......
They pack ice cream in it at(they sell ice crea the gas station m in
cones) and they just throw it away.



I can see what you're trying to do and I can see the fun in trying it, but
unless you're very good with a tig welder I wouldn't try that at all, I
really dont fancy my liver being spread over to large an area, it's just
fine where it is now.


If the goal of this exercise is to supply a steady stream of CO2 which can
be easily regulated / shut off, why don't you use a setup using baking soda
(NaHCO3) and a suitable acid like HCL or vinegar if you're a pussy :-)


I can't remember where I saw this but a setup with a couple of containers,
one with the acid in a ballon in a slightly presurized container, say 0.1bar
(1m water column), with a hose comming from the ballon to the next container
that contains the bakingpowder with about 2-3 cm of water on top (it wont
all disolve right away but will when the concetration goes down after time)
and another hose comming out to you tank, bubler, regulator whatever...

The theory is that when you add the acid to the saturated bakingpowder
solution the reaction releases CO2 which increases the pressure thus
preventing more acid to flow into the mixing container. When some of the CO2
is used the pressure will drop, allowing some acid to drip into the main
reactor, reacting with some baking powder thus creating some more CO2 until
the pressure reaches a equilibrium at arround the 0.1 bar mark...

The potential yield of this would be quite large, ie. pretty much governed
bu how fast you can supply the acid and how fast the CO2 gas can be used. On
the other hand you should be able to stop using any CO2 at all and the
reaction should stop itselfe because the pressure gets to high for any more
acid to flow into the main reactor and nothing more happens.

It would probably be a good idea to include a oneway valve in the hose
comming from the acid container and oanother in the hose comming from the
main reactor and a couple of stop valves would probably be called for as
well....


The chemical reaction is:

NaHCO3(aq) + HCl(aq) = CO2(g) + H20(aq) + NaCL(aq) + energy


I haven't build this one yet, but where I live baking powder is dirt cheap
and so is the HCl, one could use other acids if no HCl is available.

I would think that standard PVC drain fittings could be used, the pressure
is well within reach of standard schedule40 pipes and fittings, but one
could use schedule80 if paranoid. the hoses could be solicone of standard
vinyl hoses, as long as they're monitored close they should be fine...


What do you think, Is this approach even more insane than the Dry Ice in
container method, as far as I can see it should work just fine, just haven't
hade the time to source some materials yet...

/Morten




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