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Author: Subject: The short questions thread (2)
Sedit
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So if I understand correctly then assuming the temperature of the flame is 2(were working figuratively here) then the real temperature is to the 4th power of two or 16? That is an insane amount of loss. Given that the radiant energy could be reflected back on a target wouldn't we be able to focus the energy back on the target and increase the temperature exponentially(theoreticaly).

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gsd
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Sorry for the confusion. I should have said: "radiation losses are PROPORTIONAL to the 4th power of absolute temperature of the flame"
The proportionality constant being Stephan-Boltzman constant. (=5.67*10^-8) J/(sec*M^2*K^-4))

 Quote: Originally posted by Sedit So if I understand correctly then assuming the temperature of the flame is 2(were working figuratively here) then the real temperature is to the 4th power of two or 16? That is an insane amount of loss.

NO. The real temperature of the flame is its adiabatic temperature. The S-B law gives you amount of energy readiated by the hot object at a given temperature.

 Quote: Originally posted by Sedit Given that the radiant energy could be reflected back on a target wouldn't we be able to focus the energy back on the target and increase the temperature exponentially(theoreticaly).

Yes. But again the maximum temperature you can achieve this way is the Adiabatic Flame Temperature.

gsd
Sedit
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I got it now I think, thanks for the effort Gsd.

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"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
UnintentionalChaos
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 Quote: Originally posted by Sedit Its not really a factor of needing to graduate or anything of that nature its just that I used something simular as This to melt lead a few days ago for the reduction of Pottasium nitrate and it got me to thinking of the range of temperatures that could be achived using different fuels in a simular device. It worked very well and burned for 45 minutes or so on a single charge which kind of impressed me to say the least. I was under the impression that there is an upper limit to the temperature at which a specific fuel can burn at assuming complete combustion and is independent of flame size.

Yes, there is a limit, but like I said, heat transfer lowers the temperature of smaller flames while lack of oxygen influx limits that of larger flames. There is a way to calculate a theoretical flame temperature (adiabatic flame temperature), but you need heat capacities over a very wide range of temperatures for the gases produced and the resulting number is not without flaws.

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GLC - Kovats

The Kovats retention index is a useful way of systematizing GLC stationary phases. There is a useful list of RI here:- http://www.flavornet.org/flavornet.html

But this site also lists something called Ethyl Ester Retention Indexes

What are these? I would have thought they would be, analogously to the Kovats, relative to fatty acid ethyl esters, so that, on any given stationary phase, ethyl acetate = 200, ethyl propionate = 300, ethyl n-butyrate = 400, etc, but, from the values given in this site, that is not the case.

Edit:-
On close examination I think the Ethyl Ester RI data are bogus. Most compounds are represented twice with two sets of radically different data. My best guess is that these RI data ware computed from the Kovats data and that the deviations from the correct values are rounding errors. The duplicate entries must be human error.

bbartlog
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It's my understanding that if I have sodium bisulfate in aqueous solution, I can then (assuming it's concentrated enough) add ethanol and disproportionate it such that I end up with sodium sulfate in the aqueous phase and sulfuric acid in the ethanol.

Will the same thing work with ammonium bisulfate?
1281371269
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Would melting Pb in Sulphuric acid purify it, or would it react with the acid? Is there a simple way to purify it?
It's a pretty small bit, about 50g max.
Da_Boss
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Does anyone know how to synthesize calcium hypophosphite from red phosphorous or phosphoric acid?
Sedit
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Mossy how would you plan on keeping the Sulfuric acid from vaporizing when you melted the lead in the first place? I think worried about if it would react is a non issue here because it won't work the way you want it to anyway.

If you want to "clean" the lead I think you would be better just melting it down, Stirring and skimming the slag that forms on the top leaving a purer lead at the bottom. If its an alloy of lead such as solder is then your going to have to go a different way to seperate the alloy if you can at all.

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"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
1281371269
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Lead has a lower melting point than sulphuric acid's boiling point, by about 10 degrees. As the piece is small enough to fit in a test tube and be covered over with acid, it could be kept molten for at least a few minutes before the acid all boiled away.
Sedit
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10 degrees is not much of anything. Odds are before you have a chance to melt all of the lead there will be a ten degree difference and your H2SO4 will start to boil away.

What exactly are you attempting to do with the lead?

Knowledge is useless to useless people...

"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
1281371269
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There's no usage in mind, not currently anyway. I just wanted to purify it and wondered if this was viable.
Sedit
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Sorry if I wasn't clear on what I ment. What the usage as in what do you plan on clearing out of the lead. Dirt, oxidation, or other metals alloyed with the Pb?

Knowledge is useless to useless people...

"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
1281371269
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Well anything I can really - this would deal with other metals, but actually that's probably a minimal amount of the contamination anyway.
Sedit
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In that case I would really think your best bet is to just melt it and skim any slag that forms off the surface until no more slag forms and the lead starts taking on a blue/blackish oxide coating. Let it cool and scape all the edges of the block off and you would be left with more then likely pure enough lead for most reasons.

Just my two cents on it maybe someone would be able to give you a better way to clean it. I have done this many times, Just the past few days matter of fact on some down right dirty lead covered in dirt and organic material and god knows what. Just stirring the molten Lead brings up all the crap and I would just periodicly scoop this out until it stoped comming out leaving me with lead I used to reduce some nitrate.

Knowledge is useless to useless people...

"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
DJF90
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Can lead not be purified electrolytically like copper? Shouldnt be too hard to set up if its possible, and you should get some pretty pure lead out of it.
UnintentionalChaos
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Just throw the lead in a crucible, melt, and pour the clean metal out from under the slag layer into water.

It's not very expensive to just buy pure material either...and 50g is maybe 40 cents worth of 99.9% material.

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'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
JohnWW
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If you had a sufficiently large amount of Pb, and zone-refining heating equipment, you may be able to do it by zone refining, in which a narrow zone of Pb is kept molten in a long steel (or other impervious material) cylinder by heating coils, and slowly moving the heating coils along its length, so that highly pure Pb crystallizes behind the molten zone, and the impurities are swept along in the molten zone. However, this would work only if the metallic impurities formed eutectic mixtures with Pb with melting-points below that of pure Pb.

[Edited on 3-11-09 by JohnWW]
UnintentionalChaos
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 Quote: Originally posted by JohnWW If you had a sufficiently large amount of Pb, and zone-refining heating equipment, you may be able to do it by zone refining, in which a narrow zone of Pb is kept molten in a long steel (or other impervious material) cylinder by heating coils, and slowly moving the heating coils along its length, so that highly pure Pb crystallizes behind the molten zone, and the impurities are swept along in the molten zone. [Edited on 2-11-09 by JohnWW]

That has got to be the most useless recommendation I've ever heard. Seriously?

Department of Redundancy Department - Now with paperwork!

'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
12AX7
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Well, it might be economical for extracting values. Gold and silver form eutectics with lead, which would melt and be carried along the melt zone. Lead is valuable to precious metals recovery because it's cheap and sticks to everything of value (the gold and silver).

Tim

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Quote: Originally posted by UnintentionalChaos
 Quote: Originally posted by JohnWW If you had a sufficiently large amount of Pb, and zone-refining heating equipment, you may be able to do it by zone refining, in which a narrow zone of Pb is kept molten in a long steel (or other impervious material) cylinder by heating coils, and slowly moving the heating coils along its length, so that highly pure Pb crystallizes behind the molten zone, and the impurities are swept along in the molten zone. [Edited on 2-11-09 by JohnWW]

That has got to be the most useless recommendation I've ever heard. Seriously?

You could purify it one atom at a time. Use an electron beam to sputter atoms off a lead surface and ionise them. Then accelerate them in an electric field and use a magnetic field to deflect them according to their isotopic mass. Collect the different isotopic masses in various target bins.

You could probably modify an old mass spectrometer to do the job.

Run the machine for, well, rather a long time, and you eventually have isotopically pure lead that you can use for lead-lights, solder, or whatever.
merrlin
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 Quote: Originally posted by DJF90 Can lead not be purified electrolytically like copper? Shouldnt be too hard to set up if its possible, and you should get some pretty pure lead out of it.

A keyword search of "Fundamental Aspects of Electrometallurgy" found this reference:

Dendritic electrocrystalisation of lead from lead nitrate solution. Surf. Technol. 1985; 26:177-83

I imagine that it would be a high purity, low volume process.
mr.crow
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Quote: Originally posted by UnintentionalChaos
 Quote: Originally posted by JohnWW If you had a sufficiently large amount of Pb, and zone-refining heating equipment, you may be able to do it by zone refining, in which a narrow zone of Pb is kept molten in a long steel (or other impervious material) cylinder by heating coils, and slowly moving the heating coils along its length, so that highly pure Pb crystallizes behind the molten zone, and the impurities are swept along in the molten zone. [Edited on 2-11-09 by JohnWW]

That has got to be the most useless recommendation I've ever heard. Seriously?

You could purify it one atom at a time. Use an electron beam to sputter atoms off a lead surface and ionise them. Then accelerate them in an electric field and use a magnetic field to deflect them according to their isotopic mass. Collect the different isotopic masses in various target bins.

You could probably modify an old mass spectrometer to do the job.

Run the machine for, well, rather a long time, and you eventually have isotopically pure lead that you can use for lead-lights, solder, or whatever.

For solder, lol

Sounds like the Calutrons used to enrich the uranium for Little Boy. Don't let any governments find out!
12AX7
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Isotopically pure lead is rather valuable. The isotope descended from polonium, I think, decays enough to be a concern in flip-chips, where solder is bonded directly to the die. A single alpha decay can rip through a lot of silicon.

Tim

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1281371269
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I think I'll go with melting it down, though it's barely enough even to do that. Point of interest - I got it from the inside of one of those used and glued back together bullets that you can buy in military museums.

Thanks for all the help.
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 Sciencemadness Discussion Board » Fundamentals » Miscellaneous » The short questions thread (2) Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues