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Author: Subject: Idea for simple and efficient HNO3 via NO2
Junk_Enginerd
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[*] posted on 4-7-2020 at 08:14
Idea for simple and efficient HNO3 via NO2


So I've been trying out various methods of making HNO3 as an amateur. Most of them have either failed, or have been very slow and inefficient.

I had a few ideas today and I wanted someone more competent to have a look at the concept.

So far I've been routing NO2 through a bubbling stone in ice cold water, generated via HCl+Cu+NaNO3. Works OK I guess. I ran out of HCl but wanted to keep going, so I switched to NaHSO4(sodium bisulfate)+NaNO3+heat.

I noted that this combo also generates oxygen gas, which should be a plus since I can't get any H2O2 to serve as oxidizer in the water. More importantly, I noted that its boiling point is 21°C, so condensing it to a liquid is a piece of cake.

Idea/Question 1: Why bother bubbling gaseous NO2 through water for HNO3 instead of introducing it in a liquid state? Wouldn't the liquid react much better? I've never seen anyone mention liquid NO2, only bubbling. Also, gas only has a limited contact time with the water before it reaches the surface and is lost. The liquid would have all the time in the world to react to HNO3.

I then went ahead and tried it. I set up a graham condenser, cooled it with ice water, and heated a test tube with NaNO3 and NaHSO4. Got lots of NO2 as expected, and it condensed as expected. It was, however, a little more viscous/sticky than I thought, and it didn't really want to leave the condenser. This is where I had:

Idea/Question 2: What about tilting the graham condenser a bit, just enough to let the liquid NO2 pool in every loop of the spiral, and then flushing it out with a minimum of water? This exposes a small amount of water to an ever increasing amount of liquid NO2, in a fairly oxygen rich environment. I'm thinking the liquid that comes out should be exceedingly pure and very concentrated HNO3, no?

It seems like the ideal setup of making HNO3 by the NO2 route. Am I missing anything?
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Syn the Sizer
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[*] posted on 4-7-2020 at 08:27


Do you have a distillation set? If you have NaNO3and NaHSO4 you could synthesize HNO3 from just those 2 reagents.

No bubbling through H2O needed.

Here Tom from E&F/E&I does it.
https://www.youtube.com/watch?v=VLOY-Jp2w1I&t=5s

Here is the myst32YT link he references in his video.
https://www.youtube.com/watch?v=TtPiwbRA4N8

I used this same method with sodium acetate to make my first little bit of GAA I used to synthesis pentyl acetate.

[Edited on 4-7-2020 by Syn the Sizer]
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Junk_Enginerd
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[*] posted on 4-7-2020 at 08:42


Quote: Originally posted by Syn the Sizer  
Do you have a distillation set? If you have NaNO3and NaHSO4 you could synthesize HNO3 from just those 2 reagents.

No bubbling through H2O needed.

Here Tom from E&F/E&I does it.
https://www.youtube.com/watch?v=VLOY-Jp2w1I&t=5s

Here is the myst32YT link he references in his video.
https://www.youtube.com/watch?v=TtPiwbRA4N8

I used this same method with sodium acetate to make my first little bit of GAA I used to synthesis pentyl acetate.

[Edited on 4-7-2020 by Syn the Sizer]


Well I'll be fucked. That's pretty obvious now that you've said it. I was so close to coming to that conclusion lol. Since the reaction gave off NO2, O2 and H2O, I thought "well isn't that all you need for HNO3...? and in stoichiometric quantities too?" but I also thought it can't possibly be that simple, and someone would have mentioned that instead of bothering with bubbling.

Thanks a lot, that makes all this even better than I thought! So the acid coming out would be pretty much maximum concentration then? The only water contaminant source ought to be whatever moisture is bound in the nitrate or bisulfate, right?

Sodium bisulfate really is one hell of a practical chemical to have around, what with sulfuric acid being impossible to find. Thanks pool people!

Sweet. I've intended to make some GAA as well, so I guess I'll keep the setup around. What would one use pentyl acetate for? Just for the nice smell?
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Syn the Sizer
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[*] posted on 4-7-2020 at 08:49


Believe me, I had the same thought when I first saw the procedure. I realized with sodium bisulfate, I could even make HCl at home with simple non-iodized table salt if I was in a pinch and couldn't get to a hardware store.

It should be high concentration but you will still want to distill it one more time. If you are bubbling the produce NO2 through H2O like Tom did I would use a 2nd suck back trap using an empty bottle in the middle, as you saw in the video even an inverted funnel could still suck back and ruin your product, at least an empty bottle will catch the dilute acid before it hits your product.

I made this mistake producing ammonium, I walked away for 2 min and it sucked back into my reaction vessel ruining my 1.5hrs worth of work.

Yep, pentyl acetate smalls like bananas, we made isopentyl acetate in school but I only had 1-pentanol at home.

[Edited on 4-7-2020 by Syn the Sizer]

[Edited on 4-7-2020 by Syn the Sizer]

[Edited on 4-7-2020 by Syn the Sizer]
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