Naked Science Forum
Life Sciences => The Environment => Topic started by: Peter Ridley under another name on 27/05/2011 12:21:02
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I am following up on what Pete Ridley was asking about regarding the size of the different air molecules http://www.thenakedscientists.com/forum/index.php?topic=38675.0 (http://www.thenakedscientists.com/forum/index.php?topic=38675.0). I think that most of us know that ordinary party balloons filled with He deflate more quickly than ones we blow up ourselves because the He molecule is smaller than other gases in the air and escapes more easily through pores in the usual latex rubber balloon. I found a question that was asked a couple of years ago about CO2 seeming to escape from a latex balloon even faster than He does http://www.natscience.com/Uwe/Forum.aspx/chem/9671/carbon-dioxide-filled-latex-balloons (http://www.natscience.com/Uwe/Forum.aspx/chem/9671/carbon-dioxide-filled-latex-balloons).
The discussion there wandered off elsewhere without really answering the original question, a bit like what happened to Pete Ridley’s question here, but one person did give a link to a book Irwin and Rippe's intensive care medicine
http://books.google.com/books?id=IhDFIj-PoucC&pg=PA48&lpg=PA48&dq=balloon+latex+diffuse+rapidly+co2+OR+carbon-dioxide&source=web&ots=_Ib_fjHAbh&sig=jf7hwFKOF9x_%3Cbr%3Erx89W2c5UAZ3BDw&hl=en&ei=UXePSaPrOYzQMcORoZEL&sa=X&oi=book_result&resnum=5&ct=re%3Cbr%3Esult#v=onepage&q&f=false (http://books.google.com/books?id=IhDFIj-PoucC&pg=PA48&lpg=PA48&dq=balloon+latex+diffuse+rapidly+co2+OR+carbon-dioxide&source=web&ots=_Ib_fjHAbh&sig=jf7hwFKOF9x_%3Cbr%3Erx89W2c5UAZ3BDw&hl=en&ei=UXePSaPrOYzQMcORoZEL&sa=X&oi=book_result&resnum=5&ct=re%3Cbr%3Esult#v=onepage&q&f=false) that says on page 48/49 carbon dioxide defuses through a latex balloon at a rate of approximately 0.5cc per minute
I decided to try a similar experiment with balloons, filling one with CO2 from vinegar and baking powder (bicarb) and blowing up the other by mouth. Although I haven’t done this in a properly scientific way my simple experiment has shown that on both occasions when I filled two apparently identical latex balloons to about the same size (about 120mm diameter) the one filled with CO2 shrank to less than 100mm in a couple of days while the one that I blew up stayed almost unchanged. That gives a CO2 diffusion rate through the balloon of about 1cc/min.
When I get my hands on a CO2 bottle I’ll do a more scientific experiment and record the conditions and results carefully but in the meantime can anyone explain why CO2 seems to escape through a continer when ordinary air doesn’t. In his comment on the 20th April Pete Ridley talked about Professor Nisbett having trouble storing CO2 but not CH4 and that CO2 was like a needle http://www.thenakedscientists.com/forum/index.php?topic=38675.50 (http://www.thenakedscientists.com/forum/index.php?topic=38675.50) so maybe shape as well as size is important.
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Very interesting.
I would have guessed that Methane or Ethane being non-polar would be a problem.
Perhaps they are right that CO2 has a linear structure "like a needle", whereas substances like water have a V shape, and methane would have a tetrahedral shape.
If I was doing the testing, I might compare a mono-substituted halo-methane such as floromethane or bromomethane to methane.
You might also try Argon. I have a tank of that somewhere around here so I might be able to test it.
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Hello Clifford, I have no idea what a “mono-substituted halo-methane such as floromethane or bromomethane” is or how to get or make some Argon so if you do the experiment please let me know what happens. I thought of trying methane using natural gas but as that other experimenter said it is too low a pressure to blow up a balloon. The CO2 is easy and cheap.
I found another reference to balloon catheters, this time comparing CO2 and He as the shuttle (fill?) gas. The book
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Clinical application of the intra-aortic balloon pump
http://books.google.co.uk/books?id=43PX87dkJEoC&pg=PA76&lpg=PA76&dq=%22balloon+catheter%22+CO2+gas&source=bl&ots=wTCxyDvQFR&sig=6wdKgWFnpRL6U9_RsPqZbrUMsyw&hl=en&ei=KrHfTcKUMMmr8QP5oYyQCg&sa=X&oi=book_result&ct=result&resnum=3&sqi=2&ved=0CDMQ6AEwAg#v=onepage&q=%22balloon%20catheter%22%20CO2%20gas&f=false comments on how He-filled catheters need more frequent purging and refilling and it says on page 76 that “rate of helium loss 1cc per hour”, compared with the rate for CO2 of 30cc/hour quoted in the other book that I linked to previously.
It talks about the size of the percutaneous balloon catheters of 9.5F and 8.5F where F is about 1mm circumference http://en.wikipedia.org/wiki/Foley_catheter so I see that my previous comparison of the leakage rate for my CO2-filled balloons with that in a balloon catheter is invalid, however, those two comparisons for CO2 and He in balloon catheters are interesting because they show that He diffuses through the latex twice as fast as does the CO2.
I looked at those gas molecule diameters that Pete Ridley quoted in his comment on 14th April
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Quickly comparing collision* v kinetic** diameter (in Å) for the molecules of atmospheric gases of interest to paleo-climatologists, N2 (3.8 v 3.6), O2 (3.5 v 3.5), Ne (2.8 v 2.8), CO2 (3.9 v 3.3), CO (3.7 v 3.8), CH4 (3.8 v 3.8) Ar (3.5 v 3.4), He (2.6 v 2.6), Kr (3.7 v 3.6), Xe (4.0 v 4.0)
http://www.thenakedscientists.com/forum/index.php?topic=38675.0. If he’s right with those then there may be some evidence from these balloon experiments and medical use of balloon catheters that it is correct to use kinetic rather than collision diameter when considering this diffusion of air molecules through tiny pores like those in a balloon.
Looking at those diameters for CO2, He and the main atmospheric gases N2, O2 and Ar suggests that if collision diameter is the one to use then a balloon filled with CO2 would stay up longer than one filled with air and much much longer than one filled with He. On the other hand if the right one to use is kinetic diameter then we’d expect the air-filled balloon to say up much longer than the CO2 balloon and the He balloon to go down more quickly than either.
Another thing that I notice is how similar are the sizes of He and Ne (2.6 and 2.8) which makes me expect that they will both diffuse out of a balloon at a similar rate. The difference between the size of CO2 (3.3) and He (2.6) is about the same as the difference between O2 (3.5) and Ne (2.8). Because He diffuses about twice as fast as CO2 according to those two catheter books I’d expect Ne to diffuse about twice as fast as CO2 so is there any evidence that it does so?
Looking at the comment by Pete Ridley on 17th April http://www.thenakedscientists.com/forum/index.php?topic=38675.25 he quoted from a paper http://icebubbles.ucsd.edu/Publications/Huber_closeoff_EPSL2006.pdf
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For smaller gas species (mainly He and Ne) the fractionation factors are linearly correlated to the molecule size
In the other paper http://icebubbles.ucsd.edu/Publications/closeoff_EPSL.pdf that was used as the main reference there they said “Ne is fractionated 34±2 times more than O2” so I’d expect CO2 to be fractionated around 15 times more than O2 based only on size but shape might also play a part. The picture that is shown in Figure 3 of that paper looks like three balloons very close to each other. If those balloons have air in them won’t the smallest gases like He, Ne and CO2 diffuse out of the lowest into the higher ones and the other air gases like N2, O2 and Ar stay behind in the balloons? You said about trying methane but looking at the different sizes I wouldn’t expect it to be much different to air, with little loss from the balloon compared with CO2 or He but it would be interesting to know what Ar does because it has a similar size to CO2 if you use kinetic diameter like Pete Ridley said.
The rudimentary experiment that the other person and I did suggest that the balloons with CO2 in them go down because the molecules are smaller than those of the main air gases. If that is the reason then it seems that kinetic diameter should be used and this might be the answer to my question here, but am I right or not? Also, aren’t those bubbles in ice that Pete Ridley was arguing about similar to balloons, with tiny pores in them like in latex. Maybe he was right about what he said because Professor Wolff said on 2nd May
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I think that none of us has a definite molecular-level understanding of the physical process occurring at closeoff, and it would be great if someone can do the experiments in the lab to understand that better
so does this kind of experiment with balloons help at all, like yor_on asked about on 19th April.
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I use Argon with my welder. I should be able to setup an experiment easily enough. I am just lacking balloons.
I don't have any natural gas (methane) in my house, although I may have a little propane somewhere.
Methane basically looks like:
H
|
H-C-H
|
H
A halo-methane would look like:
H
|
H-C-F
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H
or
H
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H-C-Br
|
H
But, acquiring it would be a problem, although there are halo-substituted alkanes used in refrigerants.
Carbon Dioxide is unique as it is a linear molecule.
:O=C=O:
Whereas Water is a V shaped molecule.
H H
\ /
O
..
I am using the colon (:) and periods (..) to indicate unshared electrons.
I'll let yo know if I get an argon balloon experiment running.
I believe that O2 looks like :O=O: and N2 looks like N≡N
so I am surprised it is so different from the CO2.
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Hello Clifford thanks for that explanation of those
“mono-substituted halo-methane such as floromethane or bromomethane”
things and for suggesting a shape for N2 and O2.
I've made a few changes to my previous post as I had mixed up some of my thoughts about expected diffusion rates for different gases.
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The latest state of my balloon experiment is that after another day (that’s three altogether) there has been no change in the size of the balloons. I was surprised at this and can only put it down to the fact that the pores in the latex of both air-filled and CO2-filled balloons are too small for the trapped molecules to escape. Is it likely that when first blown up the pores were at a size that allowed through the smaller (assuming that kinetic not collision diameter is relevant) or needle-shaped CO2 molecules but not the larger N2, O2 and Ar molecules?
Maybe there is another explanation but if not then would this not give support to the argument made by Pete Ridley http://www.thenakedscientists.com/forum/index.php?topic=38675.0 (http://www.thenakedscientists.com/forum/index.php?topic=38675.0) about the bubbles (or balloons) of air in the deep firn of an ice sheet. Like the balloons in my experiment, the pores in those bubbles get smaller and smaller under the increasing weight of ice above as the ice sheet thickens. I thought that I’d try filling balloons and blocking them with tubes filled with squashed up frost from my freezer (it needs de-frosting but its too full of food at the minute). I scraped off the frost and squashed it as hard as I could into two tubes of plastic water pipe (22mm) then tied the filled balloons open end over the tube. Botjh went down almost straight away so I blew through the tudes and it was easy so what I though was solid packed frost (like that “firn” he was talking about?) but is wasn’t, was it. So the firn mustn’t be either until it is squashed even more into a solid lump so those pockets in the firn might be like those balloons do you think?
That diagram that he showed on 27th April got me interested in looking at the links he gave but I couldn’t get in to the first two because they want a registration number. How can I get these? I got into the third one with the pictures of ice at http://itia.ntua.gr/hsj/45/hysj_45_03_0357.pdf (http://itia.ntua.gr/hsj/45/hysj_45_03_0357.pdf) and theyr wonderful. Look at that fig 9 on page 11. The size of those balloons are tiny but still big when thinking about molecules. How small can those photos get?
Anyway, I’m off to watch the football and will come back tomorrow and see if anybody has any ideas about this.
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I have started another of those experiments with balloons, this time filling one from my tyre pump so it’s ordinary air not from my mouth because that has CO2 but that balloon didn’t go down so it can’t be much. I half-filled the other one with CO2 from soda and vinegar then blew it up by mouth to nearly the same size as the air one, with a circumference of 44 v 45 cm. That was as much again so it must have about half CO2 and half air. Let’s see what happens to those ones. I’m guessing that it’ll be just the same as the other experiments but I’ll wait and see.
It might be important so I measured the temperature at 18C and the balloon pressure was about 100mb as best I could tell from my tyre gauge. It only moved the thickness of the needle.
CliffordK, you are the only one who has talked about my question and have you done one with argon yet? I got stacks of balloons from Tesco’s store in the party section for just £2. I don’t know why nobody else is trying to help me here. Have you any ideas? I see that you only made one comment on that question that Pete Ridley asked about “Another Hockey Stick” and didn’t follow up on his other comments. Only somebody called Wiybit who changed his name to Jolley- Joliver, and ericwolff were any real help but the thread got locked too soon. I don’t know why that happened because Pete Ridley still seemed to have some more questions like I do that is why I have started this question but nobody else is helping and you said it is very interesting. I think it is and my daughter asked at school but they didn’t know. I don’t know why nobody else wants to help me with this because it puzzles me and them. I’ll tell you tomorrow how the new balloons are doing. The first ones still haven’t changed since yesterday.
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There’s a funny thing happened in my first balloon that I put CO2 into. When I caught the CO2 n the balloon the vinegar frothed up and some of it went up into the balloon and I couldn’t get it out but didn’t worry because it stayed in all right. As I told you on the 27th the balloon went down quite a bit in the first two days but stayed at that for the next two days. Now this morning I’ve found a puddle of vinegar outside the balloon but it is still not flat. Its gone down overnight to 85mm. So what’s funny is that a lot of the vinegar got out but the CO2 is still trapped inside. Anybody know why?
Wikipedia told me that vinegar is acetic acid and I found that latex gloves arent much good for strong sulphuric acid but somebody used them and it was OK http://www.sciencemadness.org/talk/viewthread.php?tid=14040 (http://www.sciencemadness.org/talk/viewthread.php?tid=14040) The vinegar I use is malt and it says its 5% acid so is the rest just water?
Why would the vinegar get out and the CO2 stay in? Ive heard about nitrile being better for this but don’t know where to get nitrile balloons.
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Possibly the CO2 is reacting with something in the balloon (rather than escaping faster than air) ... http://en.wikipedia.org/wiki/Carbonic_acid
Air is mostly N2 which is unreactive (http://en.wikipedia.org/wiki/Nitrogen#Reactions).
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It would be interesting to do this experiment in detail with lots of gases.
There are lots of complicating factors.
One is that the gases don't need to find holes through the latex to escape, they can "dissolve" in the rubber, diffuse through it, and escape.
Secondly the air outside a balloon full of CO2 will diffuse into the balloon (which is rather counter-intuitive) so the balloon is filling up as well as emptying.
Once you have taken those effects into account, if there's still anything "odd" to explain then we might need to look at the different measurements of diameters.
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Hello RD did you find something about the CO2 going into the balloon instead of going through it or is it just a guess. The latest on my leaky balloon is that it went down to smaller than a tennis ball and started to bulge at the side. I found a pin-hole where vinegar could get out if I squeezed it so I ditched that experiment. The new one I started two days ago there is no difference in the size of either balloon, one has only air and the other about half air and half CO2. 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.
I’m very puzzled by that because I know that condoms are made from latex like the balloons and they have pores. I did a google of porosity and latex contraceptives and the first one at http://www.ecp-help.org/1652/condom-use-for-herpes.html (http://www.ecp-help.org/1652/condom-use-for-herpes.html) says that In their function as a contraceptive, condoms would have to be impermeable to spermatozoa, which are approximately 3000 nm in size. HSV-2 is considerably smaller than spermatozoa, at about 160 nm, and HIV is smaller still at 125 nm. Electron microscopy of male condoms shows an absence of full-thickness pores, but occasional pits secondary to imperfections in manufacturing. Permeability depends not just on the size of any pores in the latex barrier, but also variables such as the shape of the infectious agent, surface tension, temperature, pressure and pH of the environment
The size of those sperm and herpes is much bigger than the size that Pete Ridley said the gas molecules are http://www.thenakedscientists.com/forum/index.php?topic=38675.0 (http://www.thenakedscientists.com/forum/index.php?topic=38675.0) Those sperms and herpes are 160nm and 125nm but Pete Ridley said that the air molecules are all a lot smaller and less than 1nm so if condoms let the herpes through why can they hold in the air never mind the CO2. Any ideas anybody?
OK it says that the pores don’t go right through and it also says about the shape temperature pressure and pH so it’s a very complex thing even just in a balloon never mind deep down in the ice. Even Professor Wolff said that I think that none of us has a definite molecular-level understanding of the physical process occurring at closeoff, and it would be great if someone can do the experiments in the lab to understand that better. But it won't alter the empirical facts
http://www.thenakedscientists.com/forum/index.php?topic=38675.75 (http://www.thenakedscientists.com/forum/index.php?topic=38675.75)
I’m still puzzled about why the vinegar leaked out but not much CO2 at first. Anybody any ideas?
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"so if condoms let the herpes through why can they hold in the air never mind the CO2. Any ideas anybody?"
Who says they do let herpes through ?
(apart from the Catholic church who are clearly only concerned about "truth" as it was written down about 1700 years ago)
"I’m still puzzled about why the vinegar leaked out "
"I found a pin-hole where vinegar could get out"
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Bored chemist you said some funny things that haven’t helped me. If the gases don't need to find holes through the latex to escape but can dissolve in the rubber, diffuse through it, and escape why did the balloon with air in it not dissolve those gases and go down? As for the air outside a balloon full of CO2 diffusing into the balloon and filling it, I thought that there is something called partial pressure that makes them try to go equal so if there is only 0.04% CO2 outside and 100% inside why would any go inside from outside? That needs explaining I think. And I don’t know more than one way of measuring a balloons diameter, that’s with a tape measure so please how else can I do it?
Thanks for asking about who said herpes got through the condom. I did another check and according to this one http://www.ncbi.nlm.nih.gov/pubmed/1411838 (http://www.ncbi.nlm.nih.gov/pubmed/1411838) A suspension of polystyrene 110 nm microspheres labeled with fluorescent dye served as the HIV-sized particle model in semen. They challenged each condom with this suspension for 30 minutes. The test did not include motion since stretching over the penis accounts for most pore stretching. Leakage of fluorescent dye occurred in 29 condoms (p .03). 21 condoms leaked at minimum leak rates 1 nl/s, 7 at 1-6 nl/s, and 1 at around 10 nl/s
HIV looks a bit smaller than herpes but still similar size. I might be wrong about herpes but maybe not about HIV but what is more important is how big are the pores in latex, especially the balloons I’m using. There is another site http://www.straightdope.com/columns/read/1178/can-hiv-pass-through-the-pores-in-latex-condoms (http://www.straightdope.com/columns/read/1178/can-hiv-pass-through-the-pores-in-latex-condoms) that says the size of the pores in latex gloves is about 5 microns but condoms are better but no size is given. Another site says that industry officials admit condoms have holes 50 to 500 times the size of the HIV virus
http://www.dianedew.com/condom.htm (http://www.dianedew.com/condom.htm) and that is about 5-50microns. Does anybody here know anything about the size of pores in latex balloons or condoms because the Internet gives different answers.
You also put two bits of what I said together like I said them at the same time but I didn’t. Isnt that called cherry picking? and it sounded a bit sarcastic. I said yesterday that I’ve found a puddle of vinegar outside the balloon but it is still not flat(that’s the balloons I meant not the vinegar or CO2). Its gone down overnight to 85mm. So what’s funny is that a lot of the vinegar got out but a lot of CO2 was still trapped inside
Today I said that I’m still puzzled about why the vinegar leaked out but not much CO2 at first
You haven’t explained why the vinegar got out yesterday but the balloon still had a lot of CO2 in it. Anybody know why?” I’d expect the gas to get out easier than the liquid.
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Partial Pressures may not be a major influence on rubber balloons as the rubber itself will exert pressure on the gas inside the balloon.
The Partial Pressures might, however, be an influence on Mylar balloons which may have the same pressure inside and outside.
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The difference in partial pressure of CO2 inside and outside a CO2 filled balloon is about 1 atmosphere.
The difference in partial pressure of nitrogen between the inside and outside of a CO2 filled balloon is about 0.8 atmospheres and the partial pressure difference for oxygen is about 0.2 atmospheres. The difference in pressure due to the elasticity of the balloon is rather small; certainly less than 10%.
Some materials just dissolve netter than others.
CO2 may be more or less soluble in rubber that O2 or N2. I don't know.
It seems not all condoms are created equal. The ones I have seen are tested by seeing if they conduct electricity (Ouch!).
That rules out much of a leak.
Also, as you say, you can blow them up, so we know they don't leak.
Until the vinegar leaked out, it was in the way of the CO2. Also there's the fact that the liquid would dissolve CO2 and act as a reservoir.
Measuring the diameter of the balloon isn't the whole story; you need to know what's in it, and that's not always the same stuff that you start with.
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Clifford if the balloon is exerting a pressure won’t that reduce the volume that the CO2 would otherwise reach if the balloon isn’t holding it in? Doesnt that keep the CO2 partial pressure higher? You say may and might a lot so are you just guessing.
Bored chemist if the partial pressure of CO2 in the balloon that only has CO2 in it is nearly 1 atmosphere (couldn’t it be a bit more because when I measured the filled balloon pressure it was about 100mb or a bit less) and the partial pressure outside the balloon is almost nothing how would CO2 be going into the balloon from outside like you said before? Surely the flow would be from inside to out until both are equal.
Are you saying that the CO2 dissolves into the latex instead of going through it and if you are do you know this or are you just guessing.
I found a site that talks about tyres filled with CO2 going down faster than those filled with air http://www.bikeforums.net/archive/index.php/t-154847.html (http://www.bikeforums.net/archive/index.php/t-154847.html) and somebody called supcom said he’d done an experiment and said I am confidant in concluding that CO2 leaks out of a typical bicycle tire more rapidly than air
Another one called Al1943 said he had found the same happened to him. Have you done any experiments on this or not or are you just guessing at what might happen like Clifford might be.
You said I said you can blow a contraceptive up but I didn’t say that but I did when I was little then somebody told me that it wasn’t a balloon and I got into trouble for having it.
About the vinegar I think the answer is that the vinegar ate a hole at the bottom and leaked out and stopped the CO2 getting out until I measured the balloon and put it back down with the hole out of the vinegar then the CO2 could get out. If the CO2 dissolved in the vinegar the balloon would have gone down faster. You said that
the liquid would dissolve CO2 and act as a reservoir
but does CO2 dissolve in vinegar and how much? After all it was the vinegar that released the CO2 in the first place so why would it go back in?
You said Measuring the diameter of the balloon isn't the whole story; you need to know what's in it, and that's not always the same stuff that you start with
but why would anything go into the balloon from outside. I filled one with CO2 and one with air and how would something else get into either balloon while they were still blown up with those things. Wouldn’t that make them get bigger? What makes you think that something else got in.
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A long time ago (maybe 30 years or more) there was a TV show called "Young scientist of the year".
School kids did science projects as a competition.
One of the things they investigated was this "odd" effect where CO2 leaks out of balloons more quickly than air, even though it's heavier.
I think we can all agree that the effect is real.
The explanation is another matter.
"but does CO2 dissolve in vinegar and how much?"
Yes, but I don't know- probably about as much as dissolves in water.
"but why would anything go into the balloon from outside. "
As I have said twice now, diffusion works both ways.
The air outside a balloon full of CO2 diffuses in.
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To investigate if the CO2 was reacting with the latex …
Obtain two glass carboy type jars (http://en.wikipedia.org/wiki/Demi-john)
Put a few latex balloons in one jar (not inflated).
Fill both jars with CO2
Seal the jars with manometer (http://en.wikipedia.org/wiki/File:Utube.PNG) airlock (http://en.wikipedia.org/wiki/Fermentation_lock) type device.
If the CO2 is reacting with the latex the water in that manometer (http://en.wikipedia.org/wiki/File:Utube.PNG) will be drawn into the jar.
Note variations in temperature will change both the manometer levels,
but this can be cancelled out by your control jar (with CO2 but no latex balloons).
[Jars must be kept together so are at the same temperature]
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RD did you try that experiment yourself or just read it somewhere. I couldn’t find anything about it on the Internet.
I think one of the reasons it wouldnt post first time was that Id put url= instead of utl] but why didn't it tell me what was wrong.
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That typically means you've inadvertantly used a word on the blacklist... the forum blacklist is more-or-less copied from the wikipedia blacklist (mostly words used commonly in spam posts, so often clothes, drug, or jewellery brand names), but the moderators can add other words associated with spam, or put words we would like to allow people to use to the whitelist.
Unfortunately it's not a terribly sophisticated system, and even using words that contain words on the blacklist will also prevent you from posting.
You'll just have to work out what the word it won't let you post and then either work round it or ask us to add it to the whitelist (obviously you'd need to put in extra c-h-a-r-a-c-t-e-r-s).
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Rosy thanks fr that help. Ive tried lots of things and nothing worked so will have to do as you said and look for nasty words.
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Bored chemist I couldn’t find anything about latex dissolving CO2 and mostly its the other way round so are you right about that or just guessing. One site says that the formula for pure latex is C3H3N so as you’re a chemist does that tell you anything about CO2 dissolving in it.
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A lot of people say on the Internet about their tyres going down when they fill them with CO2 but not with air. Most of them I found are talking about bike tyres like the one I said yesterday http://www.bikeforums.net/archive/index.php/t-154847.html so I did another google and found this http://velonews.competitor.com/2009/02/bikes-and-tech/technical-qa-with-lennard-zinn-large-molecules-and-short-frames_87175. It looks like Glenn who asked the question made the same mistake about the size of CO2 as what Pete Ridley was saying on 14th April about
the paleoclimatologists and their models .. What they do not seem to consider is that it is the kinetic not collision diameter that is appropriate at this stage
http://www.thenakedscientists.com/forum/index.php?topic=38675.0.
Leonard and the atmospheric chemist/bike nut Alan Hills
on that bike site seem to know about this CO2 leak happening and Alan Hills said Permeation by diffusion predicts gas leakage rates proportional to the inverse of the square root of their molecular weights. Using air as a reference the predicted leakage rates for common gases are: helium 2.7, air 1.0, nitrogen 1.02, oxygen 0.95, argon 0.85, carbon dioxide 0.81. It turns out however that the leakage rate of CO2 is huge, and the reason is that it is actually soluble in butyl rubber and is thus not constrained to normal permeation loss, it can transfer straight through the bulk rubber resulting in severe tire pressure loss on the order of a single day. .. A reference dealing with CO2 transfer through latex rubber sheds light on the loss process.
That reference he gave is to http://www.madsci.org/posts/archives/may98/895552329.Ch.r.html by Dr. John Christie of La Trobe University in Australia who is a theoretical chemist, with a particular interest in the development and application of simplistic model theories for chemical problems. My main area of interest is reaction kinetics, mechanism, and energy transfer in reactions.
http://www.latrobe.edu.au/chemistry/people/christie.html.
Dr. Christie sounds as though he is an expert in this so I’ll try to get him to help and let you know what he said or maybe he’ll talk here. I’ll ask him if he’ll help here.
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Rosy that problem seems to be c h a c h a
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I’ve E-mailed Dr. Christie and hope that he’ll get back to me but meanwhile I had a good read of what he said about CO2 in bike tyres at http://www.madsci.org/posts/archives/may98/895552329.Ch.r.html (http://www.madsci.org/posts/archives/may98/895552329.Ch.r.html). He’s an expert and said
The answer is that the carbon dioxide is much more "soluble" in the rubber that the balloons are made out of. For helium and oxygen, the chains of molecules in the balloon rubber repel the gas molecules, and they have to thread a maze, at best, to escape the balloon
Why did he put the word soluble in those commas as though it wasn’t quite right. Is it dissolving really like things dissolve into water or just going into tiny holes in the balloon and that’s not really dissolving is it?
Then he says about the CO2 having to thread a maze, at best, to escape the balloon
so that must mean it might be worse than a maize. If you look at those pictures that Pete Ridley talked about on the “Another Hockey Stick Illusion?” thread http://www.thenakedscientists.com/forum/index.php?topic=38675.50 (http://www.thenakedscientists.com/forum/index.php?topic=38675.50) on 27th April at 22:39 in Figure 11 at http://itia.ntua.gr/hsj/45/hysj_45_03_0357.pdf (http://itia.ntua.gr/hsj/45/hysj_45_03_0357.pdf) on page 369 especially at the top of the bottom picture it looks like a honeycomb kind of maize for air to get through. Isnt what Dr. Christie says something like what Pete Ridley says is in the ice?
He also said carbon dioxide is attracted to the chains of rubber molecules, and drawn in between them until it permeates the whole of the rubber. The rubber actually swells in the process. Once that has happened gas molecules can just as easily escape from either side of the balloon, and so the gas is lost relatively fast.
What attracts it to the rubber? And can the same thing happen in the ice that Pete Ridley talks about? As well does the rubber have to swell before the gas escapes? Why can’t gas just keep on going through that maize on the way out to the open air? Won’t the pressure inside the balloon push the gas out instead of letting gas in from the outside.
Any ideas anyone?
I did do a google about Dr. Christie and came across a video “Global Warming: A Scientific and Biblical Expose of Climate Change” http://www.answersingenesis.org/media/video/ondemand/global-warming/global-warming (http://www.answersingenesis.org/media/video/ondemand/global-warming/global-warming) but it was the wrong Dr. Christie. It still has some interesting stuff about climate change especially a graph at 23:30 minutes by a weather man called Mike Oard which shows how temperature change is caused by sunspots not CO2. I might start another question on that one.
Are people here just guessing at what is happening with the CO2, just like Professor Wolff said to Pete Ridley on http://www.thenakedscientists.com/forum/index.php?topic=38675.75 (http://www.thenakedscientists.com/forum/index.php?topic=38675.75) I think that none of us has a definite molecular-level understanding of the physical process occurring at closeoff, and it would be great if someone can do the experiments in the lab to understand that better
. That’s OK about balloons and contraceptives but not about air and CO2 in bubbles in ice.
I hope that Dr. Christie can be bothered to say something here like I asked him if he would.
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Dr John Christie here under a pseudonym (didn't realize that that was what I was setting up when I registered).
I am a "Mad Scientist", not a major expert, but do have some genuine knowledge in this area.
Here is a review article -- not quite on this topic, but it provides a useful clarification of some of the terms that are being used, and a diagram that displays quite clearly three different mechanisms whereby a gas might escape a container.
http://www.benthamscience.com/cheng/samples/cheng%201-1/Sandra%20E.%20Kentish.pdf
In my original MadSci reply at
http://www.madsci.org/posts/archives/may98/895552329.Ch.r.html
--"soluble" was in inverted commas as an implicit warning. I did mean soluble, but people usually think in terms of simple gas in liquid or solid in liquid solutions; solutions in a matrix of rubbery polymer as solvent are more complicated, and do not behave in exactly the same way.
-- "thread a maze, at best" meant exactly what it said. "Thread a maze" is only an option if open microchannels are available -- the first or "Knudsen diffusion" option of the three mentioned in the pdf.
On the underlying topic I have a very firm view that the ice core CO2 record is trustworthy. Regardless of the detail of mechanism or modelling, ANY diffusion process can only move a substance from a region of higher concentration to a region of lower concentration. The fact that sizable fluctuations in ice core CO2 analyses can be seen back to 300kyr or longer is a clear indicator that diffusion over the milennia has been only a minor process. The resolution of ice core analyses is 100-200yr for Vostok and most other cores; 20-30 yr for Law dome:
http://cdiac.ornl.gov/trends/co2/lawdome.html
and google for other refs.
Temporal resolution is a clear indicator of the extent of diffusion, regardless of process.
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Bored chemist I couldn’t find anything about latex dissolving CO2 and mostly its the other way round so are you right about that or just guessing. One site says that the formula for pure latex is C3H3N so as you’re a chemist does that tell you anything about CO2 dissolving in it.
As a chemist I know that formula is just plain wrong. It's close to right for nitrile gloves.
All things dissolve in all other things to some extent (unless they react).
RD's suggestion will get upset by the CO2 dissolving in the water in the manometer.
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Hello Dr. Christie thanks very much for commenting here so quickly because ideas from somebody who knows about the processes of molecular movement through pores and channels that approach the size of those molecules is really needed here. You may call yourself a mad scientist but at least you look like you understand the science. I don’t know if anyone else commenting here is a scientist so I think what you say may be more dependable. After all you do have a high qualification and are a science educator. You appear to have knowledge about my question that nobody else here seems to have so please tell me more about how those molecules move through pores and channels that are a similar size to the molecules.
Pete Ridley was asking about the size of molecules and talked about collision diameter being the wrong one and kinetic diameter being the one to use so was he wrong about that? He said that For many of the gases that make up the atmosphere there is little difference between collision and kinetic diameter, as seen in the listing below, but for CO2 this is not the case. Consequently, as the ice is compressed and pressure builds up in the pockets the CO2 molecules (and any smaller ones) escape from the pockets and move down the pressure gradient towards the surface, long after the larger gases like N2, O2, Ar and CH4 are trapped
http://www.thenakedscientists.com/forum/index.php?topic=38675.0 (http://www.thenakedscientists.com/forum/index.php?topic=38675.0) so that other thing is about a pressure difference. I think he was talking about the air in the bubbles getting squashed and the pressure inside being higher than outside so isn’t that what happens in a balloon and why the gas gets out to the air and not from the air into the balloon?
You also said about if open microchannels are available -- the first or "Knudsen diffusion" option of the three mentioned in the pdf
I haven’t read the pdf yet but will do next but Pete Ridley also talked about that Knudsen diffusion and said on one of the sites that he linked to that Some of the pores will be so small that not all of the different types of gas molecules in the air mixture can pass, allowing only the smallest ones through, including CO2, but preventing N2, O2 and CH4. Other pores will be large enough for the whole air mixture to diffuse. I also hypothesise that both Fickian and Knudsen diffusion takes place, depending upon the size of those pores, with Fickian being relevant in the upper layers of firn and Knudsen at the approach to “complete” close-off and a gradual shift in emphasis down the ice sheet
http://www.climateconversation.wordshine.co.nz/2011/03/fallen-snow/ (http://www.climateconversation.wordshine.co.nz/2011/03/fallen-snow/) so was he wrong again?
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Bored chemist you said that the formula for pure latex of C3H3N
is just plain wrong
so can you say what it really is?. You also said All things dissolve in all other things to some extent (unless they react)
but when I think of something dissolving I think of it going into a liquid and forming ions. I googled “define dissolve” and it said to make a solution of, as by mixing with a liquid; pass into solution: to dissolve salt in water
(ttp://dictionary.reference.com/browse/dissolve (http://ttp://dictionary.reference.com/browse/dissolve) which is how I picture it. I also looked at “define solution” and it said A homogeneous mixture of two or more substances, which may be solids, liquids, gases, or a combination of these
so it looks I was wrong and solids can dissolve into solids and liquids into liquids and gases into gases and all that so whats the difference between a mixture and a solution? Like the atmosphere is a mixture of different gases but is that a solution or a sponge sucks up water but are they solutions? I didn’t think they were. What makes a solution different from a mixture and how does CO2 going into latex make it a solution? Does the CO2 and latex form a homogenous mixture?
Princeton University says any combination of two different materials which don't react is a mixture, while solutions are a special kind of mixture where mixing occurs at the molecular level. Thus, all solutions are mixtures, but not all mixtures are solutions. To make the distinction clear, we'll use the phrase "physical mixture" to denote a mixture which is not a solution. So, by this definition, both muddy water and Kool-Aid® are mixtures of solid and liquid (that's how they're prepared), but only Kool-Aid is a solution
http://www.princeton.edu/~pccm/outreach/scsp/mixturesandsolutions/background.htm (http://www.princeton.edu/~pccm/outreach/scsp/mixturesandsolutions/background.htm). That tells me that if CO2 dissolves in latex then it must react with the latex but does it and if it does why does it come out again by itself.
You also said that RD's suggestion will get upset by the CO2 dissolving in the water in the manometer
and Ive read that it does do that but it also gets put out by water depending on how hot it is. If there is a full amount of CO2 in the water to start with why would any more dissolve and what would stop some coming out of the water if the temperature went up during the experiment so it could happen either way couldn’t it.
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When chemists talk about the shape of molecules, they often get it quite wrong -- including those who write textbooks! Chemists have been in the habit of playing too much with ball-and-stick or wireframe molecular models, and too little with space filling models.
Thus I hear of the CO2 molecule being in the shape of "a needle" in this thread. CO2 is approximately an ellipsoid of rotation, with a long axis around 560 pm and identical short axes around 350 pm. It is thus the shape of an American football, or a peanut. A peanut is a good one because the only way to describe the shape of a water molecule is not a boomerang or a "V-shape", but a cashew nut!
From Yelder
Pete Ridley was asking about the size of molecules and talked about collision diameter being the wrong one and kinetic diameter being the one to use so was he wrong about that?
Collision diameter and kinetic diameter both work out to be an average of sorts between the lengths of the three principal axes. That is, both are strictly larger than the smallest axis and strictly smaller than the longest axis. There is a "fuzziness" of about 10 to 20 pm in the axis length, connected with what one regards as the outer boundary of an atom -- hence the "about" in the football measurements given above. Collision diameter is well defined; kinetic diameter is much more context dependent, and for that reason alone should probably be avoided unless you are reproducing an exact context.
But in this case, if you work along the same lines as the pdf reference, you will realize that there is a lot that does not make much sense. From Pete Ridley:
Some of the pores will be so small that not all of the different types of gas molecules in the air mixture can pass, allowing only the smallest ones through, including CO2, but preventing N2, O2 and CH4. Other pores will be large enough for the whole air mixture to diffuse. I also hypothesise that both Fickian and Knudsen diffusion takes place, depending upon the size of those pores, with Fickian being relevant in the upper layers of firn and Knudsen at the approach to “complete” close-off and a gradual shift in emphasis down the ice sheet
As the pores get smaller, Knudsen diffusion clearly takes over, and the context-dependent kinetic diameter approaches closer to the smaller axis lengths of the molecule. But when the pores reach the size where they start to block the passage of some molecules, I think the view taken in the pdf is the best approach -- the description should be in terms of a different mechanism-- molecular sieving.
However, for the overall discussion purposes, the detail of diffusion mechanism is totally irrelevant! This is the most important point in my previous post. If diffusion of carbon dioxide through ice were a serious problem for the glacial record of past atmospheric CO2, then ice cores would be showing higher carbon dioxide levels, closer to present day levels, and the large variations in the record would be "ironed out" to show a fairly smooth variation. The Vostok record shows anything but that!
http://cdiac.ornl.gov/trends/co2/graphics/vostok.co2.gif (http://cdiac.ornl.gov/trends/co2/graphics/vostok.co2.gif)
Diffusion can ONLY move material from high concentration to low concentration regions -- 2nd law of thermodynamics. The mechanism of diffusion makes no difference to this, in exactly the same way that scientists can and will rule out perpetual motion machines without looking too closely at the detail of the ingenious mechanisms they are based on.
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Hello Dr. Christie Ive had a first read of “Carbon Dioxide Separation through Polymeric Membrane Systems for Flue Gas Applications” http://www.benthamscience.com/cheng/samples/cheng%201-1/Sandra%20E.%20Kentish.pdf (http://www.benthamscience.com/cheng/samples/cheng%201-1/Sandra%20E.%20Kentish.pdf) and was puzzled straight away by the start saying
A developing technology is membrane gas separation, which is more compact, energy efficient and possibly more economical than mature technologies, such as solvent absorption
Is a polymeric membrane like a latex balloon? If it is it seems to say that its not a solvent like water and the CO2 doesn’t dissolve in it so does it dissolve in latex?
The paper talks about molecules adsorbing (I hadn’t heard of that word before) along the pore walls and surface diffusion, not about dissolving in the membrane and that is interesting because Pete Ridley also asked about adsorption. On 28th February at 20:50 he talked about Professor Hartmut Frank saying this happened in the snow as it was falling. He asked Bored chemist whether or not that initial adsorption of CO2 in the snow is a chemical or a physical process (http://www.tutorvista.com/content/chemistry/chemistry-iv/surface-chemistry/absorption-types.php). My suspicion is that it is Chemisorption but as I’m not a chemist I’d appreciate your opinion. Following on from that is another question about adsorption in the deep firn, but that can be followed up later. Let’s work our way down the ice sheet looking at the different processes that Professor Zbiniew Jaworowski has been expressing concern about since 1992 and return to deep firn adsorption of CO2 and clathrate formation at a later stage
http://www.thenakedscientists.com/forum/index.php?topic=38675.50 (http://www.thenakedscientists.com/forum/index.php?topic=38675.50).
Bored chemist never had a chance to answer that question of Pete Ridley’s about adsorption because the thread was locked. Can you tell me what the answer is please and can you tell me if adsorption occurs in ice not just in snow. I googled adsorption and it says The accumulation of gases, liquids, or solutes on the surface of a solid or liquid
with a diagram of gas molecules sticking onto charcoal. If CO2 gets adsorbed does it stick to the ice and how thick does it get and does it block up pores and channels or does it go somewhere?
Another thing that paper talks about kinetic diameter like Pete Ridley did. It gives a list of kinetic diameters for N2 O2 CH4 and CO2 in table1 which are nearly like he said on 14th April at 21:38 http://www.thenakedscientists.com/forum/index.php?topic=38675.0 (http://www.thenakedscientists.com/forum/index.php?topic=38675.0).
I’ll have to read the paper again a few times to try to understand more what is being said because its hard for me to understand but I'll keep trying.
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Hi Yelder. I have not read all the posts but it is interesting to see experiments like this being done in a home/kitchen environment. A couple of suggestions to improve the results validity:
1. Use something with better quality control than party balloons. Condoms may be better if rather more expensive.
2. Use several balloons for each single test to minimise the variability of the quality of the balloon and/or method of sealing (knot??) from the experiment.
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Hello Dr. Christie Ive had a first read of “Carbon Dioxide Separation through Polymeric Membrane Systems for Flue Gas Applications” http://www.benthamscience.com/cheng/samples/cheng%201-1/Sandra%20E.%20Kentish.pdf (http://www.benthamscience.com/cheng/samples/cheng%201-1/Sandra%20E.%20Kentish.pdf) and was puzzled straight away by the start saying A developing technology is membrane gas separation, which is more compact, energy efficient and possibly more economical than mature technologies, such as solvent absorption
Is a polymeric membrane like a latex balloon? If it is it seems to say that its not a solvent like water and the CO2 doesn’t dissolve in it so does it dissolve in latex?
Yes. A latex balloon is acting as a polymeric membrane and selectively passing CO2 in this situation. And the CO2 is definitely dissolving in the latex. It is because it is more latex-soluble than the other gases that CO2 effuses more quickly. Solvent extraction as a "conventional technology" is quite a different process, involving use of a liquid solvent to selectively remove the gas, followed (if required) by releasing the gas from the liquid again. Physical means like low pressure or warming might be used for this part of the process, or chemical means via reaction. With membrane permeation technology, the required gas dissolves in the membrane, as it would in a liquid solvent, but then it is spontaneously released at the other side of the membrane where there is none of the gas initially present. So the membrane is effectively holding the other gases in and allowing the required gas to escape. The whole situation is governed by the principles of chemical equilibrium-- thoroughly covered in any college freshman course or textbook. Membrane permeation can only separate, never concentrate -- the gas on the extraction side of the membrane arrives at a lower concentration or partial pressure than that in the original sample.
Yelder again:
Bored chemist you said that the formula for pure latex of C3H3N
Quote
is just plain wrong
so can you say what it really is?.
Bored Chemist was quite right about it being the formula of nitrile rubber. Acrylonitrile is CH2=CH-C≡N which is C3H3N. So PAN is {-CH2-CH(CN)-}n , or (C3H3N)n
Latex is {-CH2-C(CH3)=CH-CH2-}n , or (C5H8)n . The lower case n indicates an n-fold repetition, and is nothing to do with the element nitrogen. This sort of thing gives plenty of scope for confusion! There is definitely no nitrogen bonded into a latex polymer.
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Hello graham.d I was going to get some condoms but then came across those people saying about their bike tyres gong down when CO2 was used but staying up with air so is an experiment needed now to show that it happens. I might get some tyres instead and a bottle of CO2 that they seem to be able to get easily if I want to do it. I’m not sure I need to bother now that Dr Christie is helping on this as he seems to know all about it.
Hello Dr.Christie, thanks for getting back so quickly again. The help that you give is like what Professor Wolff did on the “Another Hockey Stick Illusion?” but more theory like you said you are and he was using the empirical evidence for ice cores. OK so CO2 dissolves in latex and in a polymeric membrane but now you say that it effuses, not diffuses. When I googled effuse I found this “Graham's Law of Effusion” U-tube lesson that says The rapid and random motion of tiny gas molecules results in effusion, the escape of gas molecules through very small openings
http://www.youtube.com/watch?v=TropqfFqUiI&feature=related (http://www.youtube.com/watch?v=TropqfFqUiI&feature=related) and the teacher talks about helium in a balloon and why it goes down you’ve got it enclosed in a container. Its enclosed in a good balloon usually. Well the holes that it is escaping through may only be about the size of the atoms or molecules that are escaping so the helium can very gradually effuse through
She goes on to say that gases can effuse through bottles. So does that mean that effusion is the same as diffusion but just means going through tiny openings instead of in a big space?
Thanks again for helping because I expect your very busy marking exams or something. That paper you linked to gives a lot of information about the separation of gases from a mixture using a membrane and is a big help but it doesn’t talk about effusion so is it just a matter of people using the words differently. When you say that the CO2 is .. dissolving in the latex .. effuses more quickly .. but then it is spontaneously released at the other side of the membrane
would someone else say it effuses more quickly through it? I’m still puzzled about that word dissolve so Ill give an example of what I didn’t think was dissolve. A sponge has lots of little holes and water can go into those holes so there is a mixture of a liquid in a porous flexible solid but is the water dissolved in the sponge? I didn’t think so. Whats the difference between a very thin sponge and a latex or polymeric membrane?
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Yelder, a response to a couple of points in your latest.
Effusion and diffusion? It is all a matter of Latin prefixes. E(f)-fusion is out of -melting, and di(f)-fusion is through-melting. So diffusion refers to something moving through a matrix of some sort, and effusion refers to something moving out of a container. They are really the same process (or set of processes). But to say "diffusion through" or "effusion out of" is a tautology (redundancy), while to say "diffusion out of" or "effusion through" may be valid, but is more likely a mild oxymoron (contradiction).
Solutions and mixtures and holes in sponges and the like? The word dissolve relates very directly to solutions and the process of entering into a solution. These are very basic concepts in Chemistry, and probably should be discussed a little more and in more depth in chemistry subjects at secondary and tertiary level. The key concept is a matter of homogeneous or heterogeneous. In a true solution, the component substances are divided at molecular level, and any sample of about 1000 molecules or more should have the same molecular make-up with only statistical variation. In a heterogeneous mixture the divisions are "lumpy" with clumps of many molecules of each of the component substances. There is also a very important intermediate grey area with mixtures known as colloids, where the components come in lumps of size about 1 nm to 1 μm (one millionth to one thousandth of a millimetre). Bigger than single molecules, but not much bigger! Colloids have some interesting and surprising properties. Thirty or forty years ago colloid chemistry was a bit of a backwater specialization. More recently it has formed much of the basis of the modern and trendy field known as nanotechnology.
And I am not really busy marking exam papers and the like; I am enjoying a very relaxed retirement. I maintain an Honorary appointment to my Department for the small amount of professional work I might get around to doing!
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Effusion is the word usually used to describe a gas escaping through a small hole- for example a pinhole in a piece of metal foil.
Diffusion is the transfer of a material through the bulk of another material.
I can calculate effusion rates directly from the kinetic theory of gases (though I'd not like to have to- it's been a while since I studied that).
Diffusion rates are measured empirically because they depend on a lot of odd parameters. The exception is the diffusion of one gas through another (for example when you smell a gas leak) which you can calculate, and even that case is fairly complicated.
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Dr. Christie thanks for helping me on what diffusion is which I now think I understand better but not all except the bit about melting but I guess that is just the Latin and I neednt worry about it. You said
So diffusion refers to something moving through a matrix of some sort, and effusion refers to something moving out of a container
Thinking about that balloon or tyre isnt the rubber a “matrix of some sort” so is the He or CO2 doing effusion and diffusion at the same time?
I remember on the “Another Hockey Stick Illusion?” http://www.thenakedscientists.com/forum/index.php?topic=38675.25 (http://www.thenakedscientists.com/forum/index.php?topic=38675.25) on 19th April 04:02) yor_on quoted from “Carbon dioxide concentrations for the Last Millennium, Antarctica” http://doi.pangaea.de/10.1594/PANGAEA.728135 (http://doi.pangaea.de/10.1594/PANGAEA.728135) about diffusion of dissolved air through the ice matrix into the bubbles
then Pete Ridley said on 28th April at 20:50 what Professor Hartmut Frank said about preferred diffusion of CO2 into the ice matrix
http://www.thenakedscientists.com/forum/index.php?topic=38675.50 (http://www.thenakedscientists.com/forum/index.php?topic=38675.50). Then Bored Chemist said here on 31st May at 09:46 the gases .. can "dissolve" in the rubber, diffuse through it, and escape. Secondly the air outside a balloon full of CO2 will diffuse into the balloon .. so the balloon is filling up as well as emptying
http://www.thenakedscientists.com/forum/index.php?topic=39542.0 (http://www.thenakedscientists.com/forum/index.php?topic=39542.0).
You linked to a paper in your first comment here and it says in section 2.2 about The molecular sieve framework forms a well-defined repeating structure of regular channels and cages. Gas separation is dependent on the size of these channels and cages relative to the kinetic diameter of the gas. The difference in kinetic diameter of gas molecules (Table 1) dictates which molecular sieves are useful and provides an indication of selectivity [17]. For example, Zeolite 3A separates hydrogen effectively from hydrocarbon feeds because the pore diameters are ~3 Å [109]. Zeolite 4A has pore sizes of ~ 4 Å, which will separate carbon dioxide from nitrogen and methane
http://www.benthamscience.com/cheng/samples/cheng%201-1/Sandra%20E.%20Kentish.pdf (http://www.benthamscience.com/cheng/samples/cheng%201-1/Sandra%20E.%20Kentish.pdf). It also shows a picture in fig (6) of what happens.
I see the “porous hollow fibre” like a container and the wall like the membrane of a balloon or tyre with a “repeating structure of regular channels and cages” to be a matrix so does that mean that the hydrogen and carbon dioxide are dissolved into the membrane then diffuse through it and effuse out of it? Like you said They are really the same process (or set of processes)
On that business about what was right to use kinetic or collision diameter am I right to take what Pete Ridley said that it is kinetic diameter when those “regular channels” are around the size of the molecules “~3 Å” and “~ 4 Å”? I’d like to be able to clear that one up before talking about the other things in that paper “Carbon Dioxide Separation through Polymeric Membrane Systems” like the different ways to separate gases. It says There are five possible mechanisms for membrane separation .. Knudson diffusion, molecular sieving, solution-diffusion separation, surface diffusion and capillary condensation .. Molecular sieving and solution diffusion are the main mechanisms for nearly all gas separating membranes. Knudson separation is based on gas molecules passing through membrane pores small enough to prevent bulk diffusion ..
You’ve said a little bit about Knudsen diffusion and molecular sieving but I think Ill have more questions if you have time to keep on helping me.
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Hello again Dr. Christie, on this thing about CO2 inside a balloon dissolving into the latex then diffusing then effusing into the air I had another read of your answer to “Why is my carbon dioxide effusing too fast?” http://www.madsci.org/posts/archives/may98/895552329.Ch.r.html (http://www.madsci.org/posts/archives/may98/895552329.Ch.r.html) and see you said then that
'The permeation of small molecules through flawless polymer films occurs by the consecutive steps of solution of permeant in the polymer and diffusion of the dissolved permeant.' In the table for Natural rubber which follows (page III-233), the following permeabilities are given: oxygen 23.3, argon 22.8, nitrogen 9.43, carbon dioxide 153. Permeability is governed by solubility and diffusion. There is little difference in the respective diffusion coefficients: 1.73, 1.36, 1.17, and 1.25 for the four gases (note that diffusion coefficients through the polymer do not reflect either molecular size or molar mass directly). The striking difference in the permeability figure for carbon dioxide is associated with solubility in the rubber: heat of solution figures are -4.2 kJ/mol for oxygen, -0.1 for argon, +2.1 for nitrogen, but -12.5 for carbon dioxide
That seems to answer part of what I asked in my last comment about so does that mean that the hydrogen and carbon dioxide are dissolved into the membrane then diffuse through it and effuse out of it?
except for the effuse bit. I see that CO2 permeability is 6 times for O2 and Ar and 15 times N2 so does the same thing happen in ice? Am I right thinking that the – “heat of solution” figures for O2 Ar and CO2 mean that heat is generated not used http://www.google.co.uk/search?q=define+%22heat+of+solution%22&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-GB:official&client=firefox-a#hl=en&client=firefox-a&hs=rU1&rls=org.mozilla:en-GB:official&q=Heat+of+solution&tbs=dfn:1&tbo=u&sa=X&ei=BDHtTdD0Cc_C8QPDtJTDAQ&ved=0CBgQkQ4&bav=on.2,or.r_gc.r_pw.&fp=11e1338e32ed5bc&biw=1024&bih=535 (http://www.google.co.uk/search?q=define+%22heat+of+solution%22&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-GB:official&client=firefox-a#hl=en&client=firefox-a&hs=rU1&rls=org.mozilla:en-GB:official&q=Heat+of+solution&tbs=dfn:1&tbo=u&sa=X&ei=BDHtTdD0Cc_C8QPDtJTDAQ&ved=0CBgQkQ4&bav=on.2,or.r_gc.r_pw.&fp=11e1338e32ed5bc&biw=1024&bih=535)? If it is could that make ice melt a bit?
I googled - permeability CO2 ice – and found a 1958 paper “Permeation of Gases through Ice” http://onlinelibrary.wiley.com/doi/10.1111/j.2153-3490.1959.tb00041.x/pdf (http://onlinelibrary.wiley.com/doi/10.1111/j.2153-3490.1959.tb00041.x/pdf) that said One may think of two possible pathways for the permeation of gas through ice, either through pores in a dry crystalline ice structure, or through a liquid phase which might exist in the ice. In the first case, according to Graham's law, one would expect that the smaller oxygen molecules would move through the ice in greater amount than the carbon dioxide molecules, but if permeation takes place through liquid pathways carbon dioxide would pass through in greater amount because of its 20 -30 times greater solubility. The latter was clearly the case, and this strongly suggests that we are dealing with permeation through a liquid phase
I see that he says the smaller oxygen .. than the carbon dioxide molecules
then says that is why CO2 is more permeable because of liquid being there. If kinetic diameter should be used for the permeation would there need to be liquid for CO2 to permeate more easily and if liquid is there would the CO2 permeate even more easily and would it make more liquid because of “heat of solution” do you think?
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Just a quick comment on a couple of points from Yelder's latest:
Am I right thinking that the – “heat of solution” figures for O2 Ar and CO2 mean that heat is generated not used
This is quite right. However the heat is associated with entering into solution or leaving solution. If a gas is dissolving into a membrane, there will be a minute heating of the entry side and a minute cooling of a little under the same size at the exit side.
A brief technical lesson: The solubility of a material is governed by the "standard free energy of solution". This has two components, one of which is the "heat of solution" or "standard enthalpy of solution" that I quoted. The other is an entropy based term. For solid in liquid solutions, this can vary a lot. But it is usually a large positive entropy, as the relatively ordered structure of a solid is broken down into a less ordered random distribution in a liquid solvent. But for solutions of gases it is a small negative entropy that varies little for different gases or different solvents. Gases are slightly less disordered in solutions than as the free gas because their motions are somewhat restricted. So my reason for quoting "heats of solution" was because it gives a strong indication of the affinity of the gas for the matrix, and of the consequent solubility. It was not really anything to do with heat as such.
I googled - permeability CO2 ice – and found a 1958 paper “Permeation of Gases through Ice” http://onlinelibrary.wiley.com/doi/10.1111/j.2153-3490.1959.tb00041.x/pdf that said
Quote
One may think of two possible pathways for the permeation of gas through ice, either through pores in a dry crystalline ice structure, or through a liquid phase which might exist in the ice. In the first case, according to Graham's law, one would expect that the smaller oxygen molecules would move through the ice in greater amount than the carbon dioxide molecules, but if permeation takes place through liquid pathways carbon dioxide would pass through in greater amount because of its 20 -30 times greater solubility. The latter was clearly the case, and this strongly suggests that we are dealing with permeation through a liquid phase
I see that he says
Quote
the smaller oxygen .. than the carbon dioxide molecules
then says that is why CO2 is more permeable because of liquid being there. If kinetic diameter should be used for the permeation would there need to be liquid for CO2 to permeate more easily and if liquid is there would the CO2 permeate even more easily and would it make more liquid because of “heat of solution” do you think?
It is important to understand the context of this paper. It is written by a biologist whose reason for pursuing this enquiry has to do with the survival of plants through the Canadian winter. He is actually doing the experimental work at temperatures that are not extreme -- just a few degrees below freezing.
You have been contending that kinetic diameter of CO2 is smaller than that of O2 or N2, and that kinetic diameter rather than collision diameter should be used in these diffusion studies. If you are right, then his conclusion (that liquid brine channels must be an important factor) is invalidated.
If kinetic diameter should be used for the permeation would there need to be liquid for CO2 to permeate more easily and if liquid is there would the CO2 permeate even more easily and would it make more liquid because of “heat of solution” do you think?
(Hope it is not bad form to re-quote) Let us get the logic of this into place. He has MEASURED diffusion rates, and INFERRED that liquid channels must be involved to explain why CO2 diffuses faster than O2. If you are right and he is wrong about the diffusion treatment in the absence of liquid channels, then that undermines his INFERENCE but has absolutely no effect on his MEASUREMENTS. There is no question of CO2 permeating even more easily, and as explained above, release of "heat of solution" in this context is not enough to melt anything.
His study makes some other telling points:
-- that the rate of diffusion of all three gases is more than a million times slower in ice than in water,
-- that diffusion rates fall off rapidly with decreasing temperature (though he only explores temperatures relatively close to melting point, so this trend might not continue).
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Hi Bored chemist, in your last comment you said
Effusion is the word usually used to describe a gas escaping through a small hole- for example a pinhole in a piece of metal foil
I think that one of the difficulties that many of us lay people have is the different way that people, even scientists, use the terminology. Elsewhere effusion is described as you did but with the rider “into a vacuum” (although one source said “Effusion is the escape of a gas through a small hole into a vacuum or area of lower pressure”). Pete Ridley gave a link http://www.thenakedscientists.com/forum/index.php?topic=38675.0 (http://www.thenakedscientists.com/forum/index.php?topic=38675.0) 14th April at 09:36) to an animation http://www.youtube.com/watch?v=0uBK7VxT00E (http://www.youtube.com/watch?v=0uBK7VxT00E) that does that and describes how to calculate effusion rates directly from the kinetic theory of gases
so it might help jog your memory.
Pete Ridley went on to say but imagine that the bubble is an air pocket in an ice sheet approaching close-off, with all excepting one pore closed to all molecules (CO2 included). Imagine also that the hole size of that single pore is just larger than 0.33nm (the kinetic diameter of CO2) and that the red balls are CO2 molecules (N2, O2 and CH4 molecules present but not shown because they can’t escape but are still bouncing around inside in far larger quantities than CO2). Also imagine that the pore is not giving access to an empty space as shown but access to an equally small channel linking to another similar air pocket in a chain of such air pockets. Does that very simplified picture of the structure within the ice/firn help to clarify the basis of my main question? Does that very simplified picture of the structure within the firn/ice help to clarify the basis of my main question?
.
I see that you didn’t offer any help about this on that thread which is a shame because he needed it. Let’s hope that he’s watching this one and learning from it like I am.
Dr Christie’s explanation on 4th June at 00:29, involving going back to the Latin origin then talking about The key concept is a matter of homogeneous or heterogeneous. In a true solution, the component substances are divided at molecular level
has helped me understand this a lot better but perhaps not fully. My understanding of the terms dissolve, diffuse and effuse were much too restricted. What I now understand the different terms to mean are:
- “to dissolve” is to form a homogenous mixture of several different substances,
- “to diffuse” is to move within (a vacuum, a fluid, a solid),
- “to effuse” is to move out of (a vacuum, a fluid, a solid),
(is another term “to infuse”, meaning to move into (a vacuum, a fluid, a solid) is required?)
In the context of this discussion we are specifically talking about individual molecules.
You said Diffusion is the transfer of a material through the bulk of another material
and I see the significant word there being “bulk”. Dr. Christie said diffusion refers to something moving through a matrix of some sort
and that puzzles me. From the definitions that I use above water going into a sponge and being squeezed out again is not dissolving (infusion?), diffusion and effusion because the substance of the sponge is not present as free molecules. Both water and sponge are “material” (per your definition of diffusion), the water is “something” and the sponge is “ a matrix of some sort” (per Dr. Christie’s definition). Despite that I do not think that water that has entered, permeated and been squeezed from a sponge has dissolved (infused?) diffused and effused because it does not form a homogenous mixture at the MOLECULAR level.
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. Is that what you and Dr. Christie are referring to as dissolving, diffusing and effusing into the outside air? If so, what is the appropriate measure of the gas molecules size when the air holes in the fabric are large enough for them to escape?
When I googled –effusion "into a vacuum" video – I came across “Chemistry: Effusion and Diffusion” http://thinkwell.mindbites.com/lesson/4721-chemistry-effusion-and-diffusion (http://thinkwell.mindbites.com/lesson/4721-chemistry-effusion-and-diffusion), part of a series of Chemistry course lectures taught by Professors Harman, Yee, and Sammakia available from Thinkwell, Inc. http://www.thinkwell.com/student/product/chemistry (http://www.thinkwell.com/student/product/chemistry). The scientist presenting the lecture starts off talking about effusion being gases moving through a pin hole into an evacuated space and Graham’s Law. I was getting all excited – then it stopped and asked for $2.97 to see the rest.
You also said Diffusion rates are measured empirically because they depend on a lot of odd parameters. The exception is the diffusion of one gas through another .. which you can calculate, and even that case is fairly complicated
Dr. Christie agrees with you about the complexity of this subject and as Professor Wolff said on "Another Hockey Stick Illusion?" about the processes in the deep firn of an ice sheet I think that none of us has a definite molecular-level understanding of the physical process occurring at closeoff, and it would be great if someone can do the experiments in the lab to understand that better. But it won't alter the empirical facts[/quote http://www.thenakedscientists.com/forum/index.php?topic=38675.75 (http://www.thenakedscientists.com/forum/index.php?topic=38675.75).
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Dr. Christie E-mailed today that he
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
so I'll post his response to my previous comment on his behalf.
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Hi Yelder
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.
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 -.
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Argh. Am getting very fed up of this spam filter. Have now added enjoyable to enjoy, enjoyed and enjoyment on the whitelist!
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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.
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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
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
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”.
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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 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
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.
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.
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
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fcdiac.esd.ornl.gov%2Ftrends%2Fco2%2Fgraphics%2Fvostok.co2.gif&hash=5281061516129cda4abdff3868a6e6f2)
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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Hi John (damocles) thanks for having a stab at explaining that sudden collapse of the balloon with ½ CO2 and ½ air. It’s now down to 200mm diameter from the original 440mm while the air-filled one remains at 430mm (down from 450mm). Perhaps it is worth mentioning that the original (uncoloured) balloon that I filled with air about a month ago is still fully inflated. Hi John (damocles) thanks for having a stab at explaining that sudden collapse of the balloon with ½ CO2 and ½ air. It’s now down to 200mm diameter from the original 440mm while the air-filled one remains at 430mm (down from 450mm). Perhaps it is worth mentioning that the original (uncoloured) balloon that I filled with air about a month ago is still fully inflated.
I propose to re-use those same balloons but swop around the CO2 and air to try to rule out a difference in each balloon’s properties.
Regarding your response to my comment about Jaworowski discussing liquid water in deep ice, I misled you on that. I should have said water in deep firn. In his 1997 paper “ANOTHER GLOBAL WARMING FRAUD EXPOSED Ice Core Data Show No Carbon Dioxide Increase” (http://www.warwickhughes.com/icecore/IceCoreSprg97.pdf) Fig. 2 Jaworoski provided an illustration of the vertical structure of an ice sheet and says .. meltwater seeps down and collect over impermeable layers. The firn density gradually increases with depth and at .83 g/cm3, firn changes into solid ice in which all pores are occluded, forming the primary air bubbles. Between a depth of 900 to 1,200m air bubbles disappear. Liquid water is contained in quasi-infinite network of capillary veins and films between the ice crystals. ..
He goes on to talk extensively about liquid water in the ice, e.g. .. liquid water is present in ice even at very low temperatures, and because many chemical and physical processes occur, in situ, in ice sheets and in recovered ice cores. These factors, discussed in References 8, 12, 22, and 24-28, change the original composition of air entrapped in ice, making the ice core results unrepresentative of the original chemical composition of the ancient atmosphere ..
He says in .. Some False Assumptions - For climatic interpretation of the ice core data the following assumptions are used:
.. (2) No liquid phase occurs in firn and ice at average annual air temperatures of 224°C or less ..
these assumptions are incorrect, and thus that the conclusions on low pre-industrial levels of atmospheric greenhouse gases are wrong .
Professor Eric Wolff said on Pete Ridley’s “Another Hickey Stick Illusion?” thread I think that none of us has a definite molecular level understanding of the physical process occurring at close-off ..
(http://www.thenakedscientists.com/forum/index.php?topic=38675.msg354373#msg354373). If we can for the moment make the assumption that Jaworowski is correct about that water in firn (and there are plenty who say that he is wrong) what effect do you think that would have on the movement of CO2 within the firn and ice?
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From Yelder's latest:
Professor Eric Wolff said on Pete Ridley’s “Another Hickey Stick Illusion?” thread
Quote
I think that none of us has a definite molecular level understanding of the physical process occurring at close-off ..
(http://www.thenakedscientists.com/forum/index.php?topic=38675.msg354373#msg354373). If we can for the moment make the assumption that Jaworowski is correct about that water in firn (and there are plenty who say that he is wrong) what effect do you think that would have on the movement of CO2 within the firn and ice?
Hmmm! I am intrigued with the idea of a Hickey Stick [;D]
This sort of post continues to miss the whole point of the evidence in the Vostok Ice core. To put it very simply:
-- Regardless of the detail of the mechanism a material (CO2 in this case) can only move from regions of higher concentration to lower concentration (else the second law of thermodynamics is violated and we can design a perpetual motion machine around the phenomenon)
-- The persistence of the sharp variations over periods of less than 1 kyr in the Vostok record is solid proof that the CO2 has NOT moved, because if it had moved, the only thing it could have done would be to have smoothed out these variations. The peaks would have had to flow into the troughs.
-- The detail of presence of liquid water or not, or fancy notions about diffusion mechanisms and bubble formation mechanisms and so on are therefore totally irrelevant. Jaworowski may or may not be right in the detail of some or all of what he has to say. It does not alter the fact that there is 100% solid proof in the ice record that the CO2 has moved less than 1 kyr through the profile in the whole lifetime of the ice sheet.
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Hi John, thanks for the prompt response.
I’m surprised that you are .. intrigued with the idea of a Hickey Stick ..
As I understand it this is what the global mean atmospheric CO2 content during the past 1000 years is claimed to be by the paleoclimatologists using measurements of air “trapped” in ice.
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(http://www-das.uwyo.edu/~geerts/cwx/notes/chap01/Image18.gif)
It looks very similar to the hockey stick claimed to be a true representation of the mean atmospheric temperature anomaly during the past 1000 years by Michael Mann
<spam link removed>
I’m sorry that I continue to miss the whole point of the evidence in the Vostok Ice core
and of lots of other ice cores
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(http://www.ferdinand-engelbeen.be/klimaat/klim_img/antarctic_cores_800kyr.jpg) but even though I accept that CO2 .. can only move from regions of higher concentration to lower concentration ..
wouldn’t those persistent .. sharp variations over periods of less than 1 kyr in the Vostok record ..
still exist if the original CO2 concentration was much much higher than the level shown in the ice core record if the rate of migration was very very slow? Could not a slow rate of migration still leave residual peaks and troughs as seen from that record? Could this then mean that .. The detail of presence of liquid water or not, or fancy notions about diffusion mechanisms and bubble formation mechanisms and so on ..
would be totally relevant?
Under those circumstance could not the claim that .. that there is 100% solid proof in the ice record that the CO2 has moved less than 1 kyr through the profile in the whole lifetime of the ice sheet ..
be more opinion than fact?
Of course, not being a scientist I could be totally wrong, but Jaworowski and his supporter Professor Hartmut Frank are scientists, the latter being highly regarded by his peers. As Pete Ridley said almost a year ago Dr. Hartmut Frank (Professor of Chemistry and Ecotoxicology, University of Bayreuth, Germany) who wrote the forward to Jaworowski’s 1994 paper, says QUOTE:
.. Prof. Jaworowski's main argument is valid and will remain valid because it is based on simple, but hard physicochemical facts. Most of the facts can be found in the old, traditional "Gmelin's Handbook of Inorganic Chemistry” - but nobody reads such books anymore today. The facts are so basic that one cannot even start a research project on an investigation of the validity of such carbon dioxide analyses in ice cores because the referees would judge it too trivial. But if one would apply proper quality assurance/quality control principles, as they are common in most other areas of application of chemical-analytical methods (for instance in drug control or toxicology) the whole building of climate change would collapse because of the overlooked fault.
And so one continues because there are so many living in or from this building. UNQUOTE
(http://julesandjames.blogspot.com/2010/07/monbiot-exonerated.html).
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wouldn’t those persistent
Quote
.. sharp variations over periods of less than 1 kyr in the Vostok record ..
still exist if the original CO2 concentration was much much higher than the level shown in the ice core record if the rate of migration was very very slow? Could not a slow rate of migration still leave residual peaks and troughs as seen from that record?
No, they definitely could not still exist; those sharp features would necessarily be the first to disappear of there were any migration of CO2 at all.
It only involves a few kyr of migration through the record to wipe them out, one kyr to completely blunt them. CO2 trapped in ice has not moved.
Under those circumstance could not the claim that
Quote
.. that there is 100% solid proof in the ice record that the CO2 has moved less than 1 kyr through the profile in the whole lifetime of the ice sheet ..
be more opinion than fact?
No
Of course, not being a scientist I could be totally wrong, but Jaworowski and his supporter Professor Hartmut Frank are scientists, the latter being highly regarded by his peers.
No disrespect to Professor Hartmut Frank, but "Ecotoxicology" points to a background in Organic Chemistrry and Medical Chemistry, which is a very different specialization to Glaciology or Atmospheric Chemistry/Physics. It is disingenuous to trot out credentials like this when you are prepared to ignore the credentials of a huge consensus of Atmospheric Scientists who have views that do not fit in with your preconceived notions.
... And (unless I hear much more effective refutation), here endeth the topic as far as I am concerned.
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Evidence has been presented to me confirming that the user "Pete Ridley" has, by his own admission, been using the false name "Yelder" to participate in this forum, referring to his own previous posts as though they were those of a third party; this is despite being asked previously to leave, and subseqently banned, owing to his repeated failure to abide by our forum rules and acceptable user policy.
Wantonly providing false personal information on the forum in this way is not acceptable.
For this reason, Mr Pete Ridley's alias "Yelder" has also been banned and renamed (for the benefit of other forum users) to make it clear that this content is also the work of Mr Pete Ridley.
Furthermore, having run its course and been thoroughly discussed, this thread has now been locked; thank you to everyone who has contributed to it.
Chris Smith