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mr.pyro
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| Quote: | Originally posted by ADP
| Quote: | Originally posted by crazyboy
looks like ADP did it too the thermometer bulb doesn't go in the liquid it goes in the vapor! |
This is true for most distillations however, I am interested in keeping the temperature of the mix below 70dC therefore I am interested in monitoring
that temperature not the vapor temperature as I would of MOST distillations. |
As is the same reason that I have done it.
I really dont care about my vacuum pump that much. It is old and not very good. I also have a gas trap that should neutralize most vapors. Its just
very annoying having NA condense in the tubes and attack my connectors.
[Edited on by mr.pyro]
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ADP
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The acid mist that does condense in my tube is no problem since I have an aspirator that just leads it into the sink. As for the tube it attacks the
plastic but doesn't really have any effect so it's no big deal.
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mr.pyro
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Yesterday after completing one distillation I noticed a color change in my pumps oil.
Heres what came out of it.
Fortunately there was little rust inside of the actual pump mechanism and most of the rust came from the outer portion of the air inlet. I cleaned it
up with some rust dissolver and gladly it looks brand new, just needs some new oil. Following, I will be buying an aspirator, but am reluctant to use
it because I live in the middle of the desert and don't want to waste the water.
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ADP
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I understand your concern, I do believe that someone built a water "recirc" pump to reduce the waste of water
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nodrog19
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Hcl
would hydrochloric acid work instead of sulfuric acid?
it is alot cheaper per mole of H+ where i live.
would Ca(NO3)2 work?
[Edited on 2-6-2008 by nodrog19]
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ADP
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Not for concentrations greater than about 31%...
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not_important
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| Quote: | Originally posted by nodrog19
would hydrochloric acid work instead of sulfuric acid?
[Edited on 2-6-2008 by nodrog19] |
Consider how aqua regia is made : 3HCl (aq) + HNO3 => NOCl + Cl2 + H2O
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nodrog19
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oh. i found a recipe for NO2 from an old book so i will do that.
heat KNO3 and NaHSO4 and it gives NO or NO2.
would Ca(NO3)2 or NaNO3 work? i can only buy calcium nitrate and have no source for KCl. 
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ADP
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Firstly, I hate to call you on this nodrog19 but what the hell are you trying to do? If you are trying a nitric acid synthesis, you DO NOT want NO2.
A review of basic chemistry concepts would lead you in the right direction for nitric acid synthesis - H2SO4 + KNO3 --> HNO3 + KHSO4. You can use
any nitrate, yes.
Perhaps you should read up on some chemical concepts before attempting to proceed with anything and always cross check something if you arent sure so
you don't get hurt. NO2 is a highly poisonous gas that will kill you if you breathe too much...
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Contrabasso
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There are some very nice vac pumps using an aspirator and a water pump recirculating the water through the aspirator. Pumps such as boat bilge pumps
or recreational vehicle tap water pumps have a reasonable pressure and flow, they tend to be 12 or 24 volts.
This way you can have a bucket of water and dump it when you change reaction, rather than paying for metered and scarce water.
Few vac pumps will stand conc acids!
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Tsjerk
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@ ADP
One way of making nitric acid is by bubbling NO2 into water. I believe some members here have done some experiments with that, I forgot the name of
the method.
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ADP
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Yes I'm aware of that method:
2NO2 + H2O → HNO2 + HNO3
Not the best for future nitrations have you...
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MagicJigPipe
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I've done that many times before. I actually find it easier than distilling HNO3. Apparently, blowing air through the solution is a good way to
oxidize HNO2 to HNO3.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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ADP
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Interesting, I've never heard of someone doing that practically? What is your method of producing NO2? Yes the nitrous acid that is formed reacts in
the following way:
3HNO2 → HNO3 + 2NO + H2O
The resulting NO is oxidized to NO2 which continues to react with the H2O and the process is redundant...
In the end I suppose the excess dissolved NO2 can be removed by applying vacuum to the solution.
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Tsjerk
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| Quote: | Originally posted by ADP
3HNO2 → HNO3 + 2NO + H2O
The resulting NO is oxidized to NO2 which continues to react with the H2O and the process is redundant...
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I can imagine that the NO produced here will be blown out together with the air used to oxidize the HNO2, aswell as a large part of the dissolved NO2.
[Edited on by Tsjerk]
[Edited on by Tsjerk]
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12AX7
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NO is oxidized to NO2 and both dissolve in solution leading to nitrous and hyponitrous acids which can also be oxidized.
Tim
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Fleaker
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There's always the hydrogen peroxide trick.
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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MagicJigPipe
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Even the first time I did this "synthesis" I got almost all NO2. At least 75% of the distillate was DARK red gas. And I just bubbled it through
water. It definitely works and still works to this day. I used 98% H2SO4 and dry KNO3.
More heat is required but it's damn easy. At one point, that's how I thought everyone did it.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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ADP
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Explain your method MJP. So you distill at a very high temp and allow lots of NO2 to come over then oxidize by blowing air through it? Interesting,
what conc. HNO3 can you attain via this method?
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497
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I too would be interested in hearing details about that. I wonder how it would work if you bubbled it into a solution of H2O2? Might help keep the
losses of NO to a minimum.
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nodrog19
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what about refluxing a mix of Ca(NO3)2 and H2SO4 in a boiling water bath?
the CaSO4 will precipitate. it only needs to be filtered, not distilled.
will 4Ca(NO3)2*NH4NO3*10H2O come apart in water (the Ca is less soluble)
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12AX7
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Ca (and Ba) precipitation with sulfate works with many compounds. The problem is the fine precipitate that is difficult to filter...
Tim
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497
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nodrog, a while ago I tried exactly what you said with the Ca(NO3)2 and believe me, it is extremely annoying to filter, it turns into a white mud.
Also, the solubility of CaSO4 is substantially enhanced by the presence of strong acids, so you will still have quite a bit of impurity left.
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Klute
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Adding H2O2 to conc. HNO3 is very dangerous! I really wouldn't consider it to oxidize any HNO2 in conc. HNO3...
I had one of the most frightening experience chemicallty-speaking when I added diluted pirahna solution to the acid recovery bottle, mainly constitued
of depleted and diluted aqua regia.
I added not more than 20mL of pirahna diluted at least 5x with dH2O to the bottle, placed the cap (never screwing it on because of possible gas
evolution), place dhte bottle at the rear of the fume hood, closed the hood, and went to the desk. 5 min after a phD student working in the same room
came in a panic asking what reaction I was doing, I answered none, he told me something in my fume hood had exploded and was releasing irratating red
fumes!
I rushe din to see acid litteraly pouring from the top of the hood, a great big red cloud (hopefully contained by the closed sash, but still very
irrating), and the meatl bars dissolving visually... Once the fumes were mostly evacuated, i washed down the hood with a water hose very thoroughly,
and then started taking evrything that was in there apart. All the metal bars were very damaged, aswell as most syringe needles, the things to attah
bar together, etc etc.
even afetr washing with over 300L water with the hose, the drops that fell on my suit while washing up eat through it overnight!
And that was with fairly dilute solutions. Maybe the sulfuric acid sensitives HNO3 in a way or another, but never never mix aqua regia and pirahna
together! Hopefully, I wasn't there when the bottle exploded, i would have suffered extreme wounds and burns, and hopefully the sash was completly
down, a thing that a great deal of people at work don't do. This story is told to any new student or trainees at work to make sure they close the
sash entirely when not working, and to keep it under your face at all times..
So I would discourage adding H2O2, whatever the concentration, to conc. HNO3. Maybe it has already been done by people without problems, but be
warned!
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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hashashan
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tried to distill some nitric acid under atmospheric pressure and bumped into some problems.
I followed the instruction in the books. Mixed 1:2 H2SO4 with KNO3 and started to distill that stuff in an all glass still.
All I got was nitric acid with 1.47 density which is not ever near to the 1.5 I was aiming at.
what could be the problem?
the other weired part was that after all the HNO3 got out of the goo in the flask, it melted into some bubbling liquid. any suggestions?
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