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The Environment / Why Does CO2 Escape From An Enclosure More Easily Than Air?
« on: 20/06/2011 21:16:56 »On 31/05/2011 10:21:16 I reported on my repeat of the balloon experiment that I started on 29th May where I had two balloons again, one filled with air and the other being half CO2 and half air. My comment after two days in which both balloons stayed the same size, wasQuoteIf the CO2 was going into the balloon like you said then the one with half CO2 should have gone down a bit by nowAfter 17 days the situation was no different and I was tempted to terminate it, guessing that the reason might be that the balloons were coloured (not natural as on previous tests) and perhaps the die/colouring reduced the size of pores in the latex or was preventing the CO2 dissolving.
I was about to terminate the experiment because my wife had complained about the tape measure I’d stuck to the floor to get the balloon diameter when I noticed that the CO2 balloon looked a lot smaller than the other and sure enough it has suddenly started to deflate. It was down to 350mm and half an hour later it was at 300mm v the original 440mm while the air one is at 420mm v 450mm. I tested the CO2 balloon in waterwhen it was at 300mm and saw no bubbles escaping through any leak but an hour later it is down to 230mm but still no sign of a leak when immersed in water.
Have any of the experts here any idea why there would be that delayed response and what is causing this sudden collapse? - Dr. Christie, please help.
I suspect that the "delayed response" is an illusion:
(1) Balloon latex does not follow Hooke's law. It is very stretchy at low pressures (low Young's modulus is the technical term) but much less so at higher pressures, almost rigid. What I think you might be seeing is a steady reduction in pressure in the CO2 balloon, but no discernible change in diameter while it remained effectively fully inflated.
(2) This effect is compounded with the fact that a reduction in volume of gas contained in a balloon is not commensurate with an equivalent change in diameter. If you observed a halved diameter, then the volume is only one eighth of what it was.
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Regarding Dr. Christie’s response of 14th June @ 19:13 it looks as though the preferential escape of CO2 v other atmospheric gases from a latex enclosure may be a different process to that covering the escape of CO2 from air pockets in ice. On the other hand, Dr. Zbiniew Jaworowski has discussed in several of his numerous papers how liquid water exists in deep ice. I propose to take a look at his ideas again and comment on them in the hopes of getting some further assistance here on that .
There is no significant escape of CO2 from deep ice levels. If you look at the Vostok results, you will see that there is significant quite sharply resolved structure in the CO2 profile for a few hundred thousand years
There are peaks and valleys, with concentrations ranging from about 190 to 290 ppm. If CO2 had migrated through the ice, structure like this would necessarily be wiped out.