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Author: Subject: Nitric Acid Synthesis
Alain123
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[*] posted on 16-6-2004 at 15:35
Nitric Acid Synthesis


I know this has been posted before, and I have done a search on it. I have not done anything to do with chemistry in one year, but now I want to continue to learn about it. Many topics that have been made about a synthesis of nitric acid are complicated, and someone like me would not understand it. I have also searched on the internet for different syntheses for nitric acid, but they don't sound right. I am looking for a simple explanation that is the least dangerous. I also do not have much equipment. I have one good 125mL pyrex flask, a cheaper but larger 250mL flask. I have rubber stoppers taped with teflon and a 9 inch glass tube connecting the two flasks, through the stoppers. I don't think the glass tubing that I have will suffice because of the fact that it is so short, and the width of the hole going through the tube is too small. Other apparatus that I have is a glass eye dropper, a 100mL beaker and a glass stirring rod. I am going to buy the chemicals once I find a synthesis for nitrc acid that I am comfortable using.

Thanks a lot.
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Darkfire
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[*] posted on 16-6-2004 at 16:03


Two ways



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Alain123
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[*] posted on 16-6-2004 at 19:01


How do I know how much potassium nitrate to put in the H2SO4 (and how much?)? I would also like to say that I want to make a very small amount of nitric acid as this will be my first time if I decide to make it, and I want to be safe. When mixing the potassium nitrate and sulphuric acid, do I mix them up and then quickly put the stopper back on which is connected to the other flask through the tubing? I'm assuming that the reaction between the two chemicals will result in nitric acid gas, right?

Sorry for all the questions, but I just want to make sure.
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[*] posted on 16-6-2004 at 20:23


I ran some quick numbers and to make a 50% conc of HNO3 I believe you will want to use 36.0gKNO3 and 50.0ml of conc. sulfuric acid. In 50ml of water I believe the yeild will be a 50% concentration of nitric acid.

I figure with 50ml of sulfuric you have 0.6mol of the acid in soln. Now to use up all the acid you would need 1.2 mol of potassium nitrate. You could only dissolve that much in 333ml of water. So I used 36 in 100ml becuase that is the water solubility of KNO3. So in this situation, obviously KNO3 is limiting. We now have 0.36mol of KNO3. 0.36 mol of KNO3 will yeild 7.2 mol of nitric acid in 50ml of water. Conc nitric is 14molar.

Finally, if you do make the acid do a qualative analysis on it. Take about 10 ml of your acid and add 7.5g Ag. Then take the soln and add 40.9g NaCl. You should get a percipitate. Mass the solid out and then run the numbers.
I hope my math skills still hold up:P

[Edited on 17-6-2004 by sanity gone]
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Alain123
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[*] posted on 17-6-2004 at 08:16


I have another question, do I really need a burner? Because I don't have one..
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Darkfire
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[*] posted on 17-6-2004 at 11:09


Yes you need a source of heat.



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[*] posted on 17-6-2004 at 21:57


Use the stove :D



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[*] posted on 18-6-2004 at 06:47


Or else try using an alcohol burner. Will not provide the same heat but the evolution of nitric acid might occur, at slooowwer rates.



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Marvin
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[*] posted on 18-6-2004 at 10:44


Darkfire, the first method will work really badly. The receiving container is in thermal contact with what is being distilled and the distillate will boil at a lower temperature. What happens practically is you form a little nitric acid which then refluxes itself to death. Raising the container off the bottom would help, but its basically a waste of time.
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Alain123
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[*] posted on 18-6-2004 at 12:44


How long will my glass tubing need to be? What about the width of the hole?
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Darkfire
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[*] posted on 18-6-2004 at 13:20


It depends, longer better.

Yeah i forgot to show it sitting on a stand my bad. Its actualy a very good method, Brainfever has had great sucess like that. It a quick drawing, chem out brainfever site for the real setup and explantion.




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[*] posted on 18-6-2004 at 14:03


distillation path length here is almost irrelvant... I think HNO3 boils about 80 C.... H2SO4 about 350....
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[*] posted on 18-6-2004 at 14:15


.....one of my dad friends had a vac. distillation of HNO3 blow up in his face....the pain was such that he was totally incapacitated......had there not been people to hand in the lab, who knew what he was doing, his injuries would have been much more severe... probably life threatening. The safety specs. certainly saved his eyesight.
HNO3 is nasty stuff..... Hot H2SO4 is nasty stuff......Hot HNO3 is really nasty.... make sure you have contigency plans if things do not follow the game plan. I would at minimum use a full face visor.
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[*] posted on 18-6-2004 at 14:29


Dont scare the poor kid... As long as he follows saftey precautions hell be ok, this isnt exactly vacume distilling.



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[*] posted on 18-6-2004 at 22:02


I really think that the beaker in a beaker / plastic baggy method will give you low yeilds, but it is quick and easy.

The size of your glass pipe just affects the time it takes, however, it might be wise to cool the pipe somehow- like a liebig condenser with a water jacket, you get the picture. If not, I'll have to post pics. But I don't know how. Can someone show me? Anyways, I tried distilling water in a 30 cm glass tube setup with no cooling, and it just came out as steam at the other end. Cooling solved that one, might help for nitric acid, is good for general distillation anyways. If you need help figuring out how to cool the pipe, ask, but I'm to tired to explain my method in detail right now.:)




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[*] posted on 19-6-2004 at 08:41


Now that i come to think about it.... most plastics are eaten by HNO3..... even more so HNO3.

For the experiment shown it needs to be a semi elastic film too.
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[*] posted on 19-6-2004 at 08:46


Proteus, do you by any chance know why that distillation setup blew up? Was it something he did or did it just suddenly go off? Seems uncharacteristic to me. :o



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[*] posted on 19-6-2004 at 09:01


Quote:
Originally posted by Proteios
Now that i come to think about it.... most plastics are eaten by HNO3..... even more so HNO3.

For the experiment shown it needs to be a semi elastic film too.


Use a martini glass with the glass stem part broken off. Seal whats left of the martini glass to the container with teflon tape just incase.




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[*] posted on 19-6-2004 at 09:41


Quote:

Use a martini glass with the glass stem part broken off. Seal whats left of the martini glass to the container with teflon tape just incase.


That's ingenious. For a larger cone, I suppose multiple layers of Al foil could be used --- Al is mostly resistant to cold HNO3, right?




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[*] posted on 19-6-2004 at 11:00


Yes right axehandle. The Al forms the outer oxide layer by oxidation due to the HNO3, which is unreactive. It is said to be passivated if I remeber correctly.



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[*] posted on 19-6-2004 at 11:41


Once I used a "plastic-reinforced Al foil inverted cone" to destill CH3CH2OH. Instead of having a beaker inside the large bucket, I installed a "V"-shaped sloped tray made of Al plate so the distilled ethanol could drip into that and then run out of the bucket through the tray (does this make sense?).

The inverted cone was filled with water and ice cubes, and I heated the bucket with a huge homebuilt alcohol burner. This was a long time ago, I was only 15, but I got what I think was 70% ethanol from it.




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[*] posted on 19-6-2004 at 12:43


Kinda makes sense, I think. Are you saying that under the inverted cone there was some sort of trough that would carry the distillate outside the boiling bucket. Instead of having a beaker there?
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[*] posted on 19-6-2004 at 12:53


Exactly. A "V" shaped trough, slighly sloped, carrying the destillate outside. It worked perfectly for ethanol.


[Edited on 2004-6-19 by axehandle]




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[*] posted on 19-6-2004 at 13:00


What were you doing your distilling in? When I hear bucket I think plastic... And if it was glass how did you make a hole in it for the trough?
hmm, I just reread some of it and did you make the reaction vessel out of aluminum foil?

If I am not completly confused you made a still out of tinfoil, now thats cool :D:cool:
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[*] posted on 19-6-2004 at 13:05


the distillation that blew up.... i think was down to stressed glassware.... this is one of my dads collegues.... when they were working in a lab... so its maybe 40 years ago now. I know it was a vacuum distillation... probably in a custom made kit.... propably soda glass..... long before people had a good idea of how to relieve stress in glassware by anealing (unlike todays glass blowing with programable anealing ovens). Above 400 ml you can get a reasonable bang.... and quite a lot of energy out of glassware failure (under vaccum). Here of course... only enough energy is required to splash the acid around a bit!
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