Pub #brownchem: @alpha137

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*** Channel started at Thursday, August 20, 1998 1:12:24 PM

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*** lizzk (gloworm4@175-255-230.ipt.aol.com) has joined channel #brownchem

lizzk: hello

alpha137: hello

alpha137: Just a second.

lizzk: ok

alpha137: Sorry, I was just fixing the web page. I found a little bit on acid rain in europe. Linked into our discn of 8/18/98.

lizzk: I see

alpha137: There are some tables giving the amounts of emissions of sulfur in different european countries.

alpha137: You can look later.

lizzk: Thats good

lizzk: I will

alpha137: I do not know what to make of this acid rain business. It is also complicated.

lizzk: Yes, very

lizzk: There are so many aspects, and then, it isn't quite just a local problem like air pollution,, but it isn;t as global as say the ozone or globabl warming

lizzk: ITs very difficult

alpha137: In the text, in a part on "The Mystery of the Unhealthy Forest" there is a stmmt to the effect that it is difficult to prove a cause and effect relationship.

lizzk: yes

alpha137: Feynmann, the famous (yet now dead) Nobel Prize physicist, said "You can know more than you can prove."

lizzk: ok

alpha137: Can we use this maxim for these environmental problems?

lizzk: I think so

alpha137: Supose that I am the Association of Coal Burning Energy Producers.

alpha137: Can I use this too?

lizzk: IT seems as though there must be some relationship to all these problems and to what we are spewing into the environment, but sometimes it is difficult to go amd say diffinitively this is the one and only cause\

lizzk: I think the ACBEP would use it to say "well we don't know that we are causing any damage, you can't prove it"

alpha137: Right, as it's president, that is what I am going to say.

lizzk: Plus, any industry has the added advantage of jobs- shutting down plants means losing jobs and no one likes that

lizzk: But that is not really related

alpha137: Have you ever read the small book "Surely you are Joking Mr. Feynmann"?

lizzk: No, but I heard it was good

alpha137: Some time you should read it.

lizzk: yes, i will, it is on my "list of books I will read when I have the chance but right now I can't"

alpha137: My point was that Richard Feynmann was talking about theoretical physics where he would "know" something not proven mathematically.

lizzk: yes, and we are talking about the very real world of environmental problems and yet it still holds true

alpha137: But later his physics idea would be put to both the mathematical test and the experimental test.

lizzk: And was he right?

alpha137: Usually, he was right.

lizzk: i thought so

alpha137: Feynmann was a very intuitive person who was most often correct.

lizzk: yes,

alpha137: Schwinger, a contempory, was less intuitive and more mathematical-proving everything. He was right too.

lizzk: YEs, wasn't he a quantam physics person?

alpha137: They both were.

lizzk: Ok,

alpha137: I took a course from Schwinger, but not from Feynmann.

lizzk: Wow!

lizzk: Didn't Feynmann live in Britian though? That would have been a bit more difficult to take a course from him

alpha137: No, Feynmann was at Cornell and at Cal Tech. He was from Far Rockaway, NYC and Schinger was also from Brooklyn, NYC or some place like that.

lizzk: Ok, nevermind,

lizzk: I dont know why i thought that

alpha137: Anyway, how are we to use Feynmann's concept of "knowing more than you can prove" in dealing with these environmental issues? Especially, since I, as President of ACBEP am going to use them too.

lizzk: The scientists will have to prove it

lizzk: OR else, the ACBEP will have a better advantage

alpha137: ACBEP has more dollars for Pub Relations and ads.

alpha137: What level of proof is enough?

lizzk: YEs, all the more reason to get "hard data" it is more convincing

lizzk: Probably enough to clearly show what is happening and some measure of the degree and speed, But not too much or it will be too late

lizzk: Plus, reasearch tends to build on each other

alpha137: Right.

alpha137: If we have a beaker of distilled water in equilibrium with the atmosphere will the pH be neutral, basic, or acidic?

lizzk: I think it will be slightly acidic

alpha137: Yes. Why?

lizzk: Because the atomosphere is always a little acidic- or at the very least, I know that pure rain is a little acidic

alpha137: Why?

lizzk: I'm assuming that is because there will always be a certain amount of chemical compounds in the air from varous natural processes, like photosysnthesis and respiration, death and decaying, etc

alpha137: Freshly distilled water will be neutral.

lizzk: BUt those are mostly CO_2 things

lizzk: Yes, but it isn't freshl;y distilled when it falls as rain, even if there are no pollutants,

alpha137: Distilled water, with no pollutants, in equilibrium with the atmosphere will have pH = 5.8 at 25C

lizzk: ok

alpha137: Rain water falling through the atm will "clean" the air picking up pollutants.

lizzk: i see, that is why there is such a problem with acid rain

lizzk: IT is trying to clean the air but it hurts other stuff

alpha137: Distilled water in equilibrium with a clean atm will have pH = 5.8

lizzk: yes

alpha137: Why?

lizzk: THe atomosphere is a little acidic

alpha137: The atmosphere is a gas!

alpha137: How can it "be a little acidic?"

lizzk: oh, yeah,

alpha137: What is in the atm? A clean atm that is.

lizzk: ok, parts of the atomosphere like nitrogen when dissolved in water make the water acidic. that is what I meant

alpha137: No, nitrogen is inert and will not be the cause of a pH change.

alpha137: What else?

lizzk: A clean atomosphere, Nitrogen, oxygen, some carbon dioxide, and other gasses

alpha137: Right.

alpha137: Of these gases you list which may be the cause of an acid pH?

lizzk: well, both nitrogen and oxygen are in the atomosphere in large quantities

alpha137: And they are intern in water!

alpha137: intern=inert

lizzk: But maybe some of them combine to form NO_x molecules

lizzk: Then the NO_x will make the water acidic

alpha137: No, there has to be an oxidation/reduction chemistry and that requires a large negative Gibbs free energy source-i.e., some reactive molecule.

lizzk: ok

alpha137: N_2 + H_2O -> nothing appreciable at room temperature.

lizzk: ok

alpha137: Ditto for O_2

alpha137: What is left? We have been here before I think.

lizzk: The carbon dioxide and those other gases

lizzk: like some argon,

alpha137: OK. What does the carbon dioxide do? Argon is inert.

lizzk: in water? like seltzer water?

alpha137: Yes, what happens with carbon dioxide in water?

lizzk: But isn;t seltzer water a little bit acidic?

lizzk: IT makes bubbles

alpha137: Yes, seltzer water is a bit acidic like pH = 5.8

lizzk: of CO_2

lizzk: I see

alpha137: It makes bubbles, why?

lizzk: ANd that is why it is so constantly that ph, because it all relates back to the CO_2 cycle

alpha137: Right.

lizzk: BUt what has happened in the last hundred years or so? The Carbon Dioxide has gone way up- so has acid rain, but then why do you mostly hear about the SOXand NOX ?

alpha137: This is going to be a point.

lizzk: ok

alpha137: I am trying to get you to supply me with this equation: CO_2 + H_2O -> ?

lizzk: carbonic acid?

alpha137: Right!

lizzk: ok

alpha137: I am still waiting for an answer about the bubbles in seltzer water.

alpha137: Why bubbles? What does that tell us?

lizzk: They are lighter than water?

alpha137: About the solution that is.

alpha137: About the solubility.

lizzk: They are not very soluble in water

alpha137: But the CO_2 is soluble to some extent.

lizzk: YEs

alpha137: If you dissolve too much sugar in water what do you call the solution?

lizzk: supersaturated

alpha137: Do you think that seltzer water is supersaturated at the moment you pop the cap?

lizzk: YEs probably

alpha137: Of course it is.

alpha137: Same principle.

lizzk: ok, but it must have a really low solubility, because if you let, it, it will completly go flat, so the onlyu reason the CO_2 is in there is because they put it in

lizzk: under lots of pressure to make it stay

alpha137: Right. This is pure chemistry!!

alpha137: The solubility of carbon dioxide in water has been exceeded by applying pressure.

lizzk: yes

alpha137: Now, you are telling me that rain drops, even in the absence of pollutants, will be acidic due to carbon dioxide>

lizzk: yes

alpha137: Isn't this, if it is raining, acid rain?

lizzk: no, because it is supposed to be like that, but yes it is acidic

alpha137: Right as rain!

alpha137: This is the natural state.

lizzk: yes

alpha137: We need to know this elementary stuff so that ACBEP does not use it to confuse the public!

lizzk: yes

alpha137: In the midwest there is a lake. The bottom of that lake contains limestone, CaCO_3. The lake is in equilibrium with carbon dioxide in the atmosphere.

lizzk: because the CO_2 from the rain is absorbed by the limestone in the lake?

alpha137: What happens: CaCO_3 + CO_2 + H_2O -> ?

alpha137: Yes, to your last stmmt.

lizzk: water plus a salt? of calcium

alpha137: The CaCO_3 (s) is a solid, the CO_2(g) is a gas and H_2O is a liquid.

alpha137: Yes, some Ca^2+

alpha137: and some ?

alpha137: What is a balanced chemical equation for this?

lizzk: CaC_2O_5?? HCO_3?

lizzk: Im working on it

alpha137: Products are going to be Ca^2+ (aq) and HCO_3^-

lizzk: I got- I was typing it in when that popped up

lizzk: I understand now

alpha137: Now, given an equation and the stmmt that it is at equilibrium between reactants and products, an equilibrium constant expression is defined. Can you give me the Keq for this reactions?

alpha137: Remember the rule?

lizzk: [Ca^2][HCO_3-]^2/[h2o][co2][caco3]??

alpha137: Close, but no cigar yet.

alpha137: Convention says do not bother with H_2O because it is essentially constant.

lizzk: oh, ok

alpha137: Likewise for CaCO_3(s)

lizzk: So it be [Ca^2][HCO_3-]^2/[CO_2]

alpha137: For our purpose we can express the [CO_2} as a partial pressure, pCO_2

lizzk: ok

lizzk: what is the pCO_2

lizzk: ?

alpha137: Right, and rearranging [HCO_3^-] = Keq * pCO_2/[Ca^2+]

alpha137: pCO_2 is the pressure of carbon dioxide in the atmosphere in this case.

lizzk: so 1atm

lizzk: ?

alpha137: At a given T there is a constant relationship between the partial pressure of carbon dioxide and the carbonic acid in solution CO_2 + H_2O = H_2CO_3

lizzk: ok

alpha137: No, 1 atm is the TOTAL pressure. 80% is N_2, 20% O_2 and some small % is CO_2.

lizzk: oh, ok

alpha137: What does this equation tell us about increasing the pressure of CO_2?

lizzk: more CO_2 will be absorbed

alpha137: And produce?

lizzk: more carbonic acid

alpha137: Right.

alpha137: If acid rain, containing H_2SO_4 for example, falls on this lake what do you expect?

lizzk: ok

lizzk: probably the lake will become more acidic, but if there is limestone on the bottom, then it will combine with the H_2SO_4 and not really change the pH

lizzk: but lots of th limestone will be used up

alpha137: OK, right.

alpha137: The implication, assuming there is lots of limestone, is what?

lizzk: The lake will stay at equilibrium and continue to be healthy (it won't become really acidic)

alpha137: Right. Here in New England the lakes are not so lucky as to have much limestone.

alpha137: Thus, they become acidic.

lizzk: so the lakes are dying

alpha137: Right.

alpha137: One of my points is that there are a number of essentially simple equilibrium reactions working in concert to describe the water chemistry.

lizzk: But the ones in the midwest do, so if you forget about the limestone bottoms, then it seems as if the problem has nothing to do with idustrialization because the lakes closest to the factories are still healthy]

alpha137: Right to your last comment.

lizzk: SO it is important for the scientist to tell people that or else the ACBEP can use that to their advantage

alpha137: Right. I guess that we may use Feynmann's "know more than you can prove," but we have to have something to back it up.

lizzk: yes

alpha137: If we have to wait for "exacting" scientific proof (beyond doubt) then we will not be able to deal with these problems in any useful time frame. It seems to me.

lizzk: YEs, i agree

alpha137: Acid rain and global warming are cases in point.

lizzk: yes

alpha137: I sat in on a thesis presentation about a study of a forest ecosystem. There were many things unexplained, yet sitting there looking at all the observations and data presented there was little doubt in my mind that acid rain had a bad effec

alpha137: If we believe that know enough to know that acid deposition is having a bad effect then what are the possible control strategies?

alpha137: I need to stop and do some other things. Want to consider this next Tuesday at the same time?

lizzk: Since the major causes of it are pollutants from cars and factories, if there was some way to curb those, it would help not only local air pollution but also acid rain

lizzk: Yes, next tues. same time.

lizzk: Thanks, I should go too

alpha137: Yes, to your stmmt on the causes. bye. talk to you Tues.

lizzk: bye

lizzk: and thank you

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