re-use NO2 and Cl2

Hi there, I'm looking for an efficient way of converting Cl2 and NO2 back to HNO3 and HCl.
is not for anything in particular just for fun, and because of the fact that I am doing at the moment lots of experimentation with MnO2 and HCl and other clorine production reactions, and as well obtaining various nitrates with HNO3 and the respective metals.

So I though it will be fun getting rid of all this nasty fumes and turn them to something useful.

the Cl2 seems easy enough: bubble in H2O and wait (from another post here in SM it should produce HCl and HClO in equilibrium, being the HClO unstable and decomposing into HCl.

for the NO2 being bubbled in H2O though I haven't found much, will it turn straight away into HNO3?

my main questions are, is this as easy as it sounds, doing this and then boiling-concentrating/distilling until azeotrope?
and how do I improve the gas absorption by the water, if I just submerge a plastic tube into a H2O beaker I suppose I'll loose lots of gas bubbling out of solution, and I'm not really up to closing the system to maximise absorption (or explosion )

Many Thanks everyone

[Edited on 25-12-2016 by exodia]

Quote: Originally posted by WGTR

Quote: Originally posted by Chemetix   In the SM library I found Absorption of Nitrous Gasses, a 1933 text but an exhaustive tome on the dynamics of NO2 absorption and quite instructive. I bought an original copy of that. Had to have it shipped from Australia to the U.S. I considered it well worth the price, and it occupies a place of honor on the bookshelf. Quote: Originally posted by Chemetix   I'll try an absorption tower and see what is possible. If you want to, you can adsorb NO2 onto silica gel. https://www.sciencemadness.org/whisper/viewthread.php?tid=48... The NO just passes through unaffected. It's best if the gasses are dry, since water is also adsorbed. In this way, dilute streams of NO2 can be concentrated, allowing an easier conversion into nitric acid, and at a higher acid concentration. Also, the silica gel is a handy way of storing NO2. To release the NO2 vapors, the silica gel can be heated up. In the linked video, the gasses weren't dried, so some water was also getting adsorbed. I'm working (off and on) on a Birkeland-Eyde reactor design. By drying the gasses going into the reactor, allowing the exit gasses time to oxidize, and then adsorbing the NO2 onto a silica gel column, I'm able to easily measure the efficiency by comparing the before and after weights of the adsorption tube. Since you're producing water in the reaction (?), perhaps that could be adsorbed in a drying column right after the gasses cool down, before the NO has time to oxidize. After time spent in the oxidation chamber, then the resulting gasses could be adsorbed in a second column, that could be weighed...? Just an idea.

Quote: Originally posted by woelen

I have actually done some experimenting with Cl2 and NOx. Cl2 and NO give orange gaseous ONCl, which quickly hydrolyses in water, but not in concentrated HCl. In the latter it dissolves, giving very nice orange solutions, looking very much like solutions of K2Cr2O7. ONCl reacts with water, giving HCl and HNO2, which in turn gives HNO3 and NO. Dry Cl2 and NO2 do not seem to react. The mix of gases becomes brown, not looking very nice. On addition of water, however, the mix of gases quickly dissolves and a colorless acidic solution is obtained. I tested this and it contains chloride. The other part most likely is nitric acid. I am quite sure that the reaction is as follows: 2NO2 + Cl2 + 2H2O --> 2HNO3 + 2HCl

Quote: Originally posted by AndersHoveland

Quote: Originally posted by woelen   Cl2 and NO give orange gaseous ONCl, which quickly hydrolyses in water, but not in concentrated HCl. In the latter it dissolves, giving very nice orange solutions, looking very much like solutions of K2Cr2O7. ONCl reacts with water, giving HCl and HNO2, which in turn gives HNO3 and NO. It is obviously in equilibrium. Nitric and hydrochloric acids in concentrated solution have equilibrium with nitrosyl chloride and chlorine: HNO3 + 3 HCl <==> 2 H2O + NOCl + Cl2 This is the same equilibrium that allows aqua regia to dissolve gold. The reaction shifts to the left in more dilute aqueous solution, or to the right in more concentrated acidic solutions. Since nitrosyl chloride does indeed hydrolyze in water to HNO2 and HCl, the equilibrium could also be written as: HNO3 + 2 HCl <==> HNO2 + H2O + Cl2 If I recall correctly, aqueous solutions of nitrogen dioxide are in equilibrium with nitric acid and nitric oxide. The equilibrium can shift either way depending on conditions. 3 NO2 + H2O <==> 2 HNO3(aq) + NO 2 HNO2 <==> H2O + NO2 + NO So we could also write the equilibrium as: 4 HNO3 + 8 HCl <==> 2 NO2 + 2 NOCl + 6 H2O + 3 Cl2 Obviously nitric oxide is not going to be able to accumulate in the presence of chlorine, since it will just be immediately oxidized. In the absence of water (or also as Woelen has demonsrated in conc. HCl) nitric oxide is oxidized by chlorine to nitrosyl chloride. In more dilute aqueous solutions, chlorine oxidizes it to nitric acid......... [Edited on 1-2-2013 by AndersHoveland]

Quote: Originally posted by AJKOER

Adding Cl2 to two parts NO2 into the same water should work also. I have performed for dilute solutions in a closed system . Expected net aqueous reactions (upon shaking to remove gas phase products): Cl2 + H2O = HCl + HOCl 2 NO2 + H2O = HNO2 + HNO3 HOCl + HNO2 → HCl + HNO3 Net: Cl2 + 2 NO2 + 2 H2O → 2 HCl + 2 HNO3 [Edited on 26-12-2016 by AJKOER]

Quote: Originally posted by clearly_not_atara

If your anhydride-forming equation is formally O2NOH + HCl >> H2O + O2NCl then the anhydride you're looking for is nitryl chloride. However the hydrolysis of NO2Cl forms HOCl + NO2H! But it can be formed from HSO3Cl + HNO3: http://pubs.rsc.org/en/Content/ArticleLanding/1958/JR/JR9580...