Life Sciences > The Environment
Why Does CO2 Escape From An Enclosure More Easily Than Air?
Peter Ridley under another name:
Dr. Christie E-mailed today that he
--- Quote ---Tried to post the following on the discussion forum, but the posting failed with an unspecified error, so I am sending it to you here
--- End quote ---
so I'll post his response to my previous comment on his behalf.
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Hi Yelder
--- Quote --- If my understanding is flawed again then please put me straight.
If I understand correctly then can you explain the difference between a balloon that has been punctured with numerous tiny holes (let’s say 10nm diameter each) and one that naturally has numerous tiny pores (let's say 0.33nm) as a result of being blown up and the latex stretched? Michegan State University Chemistry Department provides a spacefill model (which you can zoom into) of the molecular structure of latex [urlhttp://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/lipidstr2.htm#rubber/url]. This tells me that there are tiny air spaces between the fabric (a matrix of C and H atoms? With no mention of anything else, like water) which must grow larger as the fabric is stretched (as in blowing up a balloon). At some stage the spaces must become large enough to let through any trapped gas inside, like He or CO2.
--- End quote ---
I will have a try.
Firstly, the space-filling model of molecular structure shown in Prof Reusch's website is intended to show how the polymer molecules are put together in terms of the relationships and bonding of individual atoms in the molecular chain. What the model shows is the structure of a small section of an individual chain. It repeats at the purple atoms, and a single molecule of latex would typically contain between about 1000 and 10000 of these repetitions, and they do not run in a straight line.
Secondly this one molecule is fairly tightly packed in laterally with parts of chains of other molecules. In a polymer of this sort the packing cannot be perfect; there are always holes. But these are randomly sized and shaped sealed cells, not open channels (unless the rubber is perished or damaged).
Thirdly, there is no way that the tiny gaps you see are "air spaces". Any of the molecules in air are about the size of two of the dark grey carbon atoms, and there is no way that they would fit in the tiny gaps you are seeing in the model.
Fourthly, when you stretch rubber, you are not producing a regular expansion of the molecular structure. You are not stretching the chemical bonds between atoms nor even opening out the bond angles from their natural 110-120 degrees closer to a 180 degree straight line. Rather, you are actually partly unravelling a tangled series of random chain coils into a more extended chain -- a lot like trying to pull a tangle of ropes apart. Surprisingly, even some chemists in the rubber industry are not aware of this!
If you would really like to find out about how polymers work -- rubbery polymers, glassy polymers, and crystalline polymers -- I thoroughly recommend a book (a little old by now, like me) by Leo Mandelkern: "An Introduction to Macromolecules". It is an accessible and e-n-j-o-y-able read even for an intelligent layman.
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Dr. Christie, thanks very much for another very helpful comment.
PS: I see that the problem was the spam detector picking up on the word "e-n-j-o-y-able" minus the -.
rosy:
Argh. Am getting very fed up of this spam filter. Have now added enjoyable to enjoy, enjoyed and enjoyment on the whitelist!
Peter Ridley under another name:
Hi Rosy, yes, it can be a little frustrating at times, can't it, especially because it does not make it clear to a newcomer what the problem is.
Peter Ridley under another name:
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, was
--- Quote ---If the CO2 was going into the balloon like you said then the one with half CO2 should have gone down a bit by now
--- End quote ---
After 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.
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 .
I’ll first have a look at an article that I hadn’t come across until now “Doing Jaworowski justice” (http://www.greenworldtrust.org.uk/Forum/phpBB2/viewtopic.php?t=116&sid=502c043eca9509535498780bbd11b74f) because the exchanges between Ferdinand Engelbeen and Lucy Skywalker are it is along the same lines as Pete Ridley’s exchanges with others on “Another Hockey Stick Illusion?” (http://www.thenakedscientists.com/forum/index.php?topic=38675.0).
Talking about Lucy Skywalker (anyone have any information about her?) she posted an interesting guest post “Yamal treering proxy temperature reconstructions don’t match local thermometer records” (http://wattsupwiththat.com/2009/10/30/yamal-treering-proxy-temperature-reconstructions-dont-match-local-thermometer-records/) relating to Michal Mann’s original “hockey stick”.
[ Invalid Attachment ]
As Lucy concluded “There is no sign whasoever of a Hockey Stick shape with serious uptick in the twentieth century, in the thermometer records. Yet these records are clearly very consistent with each other, no matter how long the record or how cold, high, or maritime the locality, with a distance span of over a thousand miles. Neither does the Hockey Stick consistently show in the treerings except in the case of a single tree. Even with thermometer records that are incomplete and suffering other problems, the “robust” conclusion is -
“Warmist” treering proxy temperature evidence is falsified directly by local thermometer records”.
damocles:
--- Quote from: Yelder on 20/06/2011 19:10:42 ---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, was
--- Quote ---If the CO2 was going into the balloon like you said then the one with half CO2 should have gone down a bit by now
--- End quote ---
After 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.
--- End quote ---
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.
--- Quote ---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 .
--- End quote ---
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.
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