Sciencemadness Discussion Board

KMnO4 + HNO3

Mixell - 2-2-2011 at 13:50

Anyone knows what are the products of adding KMnO4 to concentrated nitric acid (68%)?
I should note that a after adding the KMnO4 to the nitric acid, some gas appeared (bubles were formed).

blogfast25 - 2-2-2011 at 14:26

Still intent on blowing himself up, without knowing why, eh?

Picric-A - 3-2-2011 at 00:00

Ask yourself; Which is the stronger oxdising agent of the two? From there work out which is going to be reduced, and to what, and which is going to be oxidised, and to what.

madscientist - 3-2-2011 at 04:28

If the evolved gasses are transparent, I would imagine you have potassium nitrate, manganese nitrate, and oxygen.

DJF90 - 3-2-2011 at 04:54

Quote: Originally posted by madscientist  
If the evolved gasses are transparent, I would imagine you have potassium nitrate, manganese nitrate, and oxygen.


Surely you mean if they're colourless?

madscientist - 3-2-2011 at 05:03

Oops... yes. Sorry.

ScienceSquirrel - 3-2-2011 at 05:23

Mixing potassium permanganate with other chemicals without doing some research first strikes me as an excellent way to lose a finger or three or an eye or two.

Mixell - 3-2-2011 at 06:34

Well, before I do anything I always first try mixing 100-50 mg of the reagents, and then trying it with a few grams, so if a violent reaction should occur, it will occur on the small-scale test.
So I assumne the reaction was as following:
4KMnO4+ 12HNO3--> 4KNO3 + 4Mn(NO3)2 +6H2O +5O2
Now it would be good to find a way to isolate the manganese nitrate...

And blogfast, I think your familiar with the over-used phrase: If you dont got anything useful to say, don't say nothing at all.

ScienceSquirrel - 3-2-2011 at 08:17

That is ignoring the power rule, the volume of a body of reactants increases as a cube but the area increases by only the square.
You must also remember that the speed of a reaction doubles with every 10C rise in temperature.
This is why a few bales of green hay in a field will never catch fire, heat is lost faster than fermentation in the bales can make it. Make a big stack of green hay though and leave it to fester and it will readily catch fire.
A reaction that does nothing much on a small scale can run out of control or explode when the scale is increased.
A lot of industrial chemistry is about dilution, cooling, etc so big multiton reactions can be run safely.
Running a quick Google on your reactants before mixing them together is just common sense.

blogfast25 - 3-2-2011 at 08:31

ScienceSquirrel:

Chemical incompatibility lists galore. I'm really not sure what Mixell's objectives are but I doubt if they're scientific...

Mixell - 3-2-2011 at 14:47

Well, I didn't think it worth mentioning (because it should be obvious), but I do check everything on Google (and here) if its possible, if its not possible, I usually conduct a small-scale experiment (with safety mask and gloves of-course). And simultaneously ask here, if the reaction dose not produce easily distinguished compounds.
And finally, blogfast, I do not know you, and you do not know me, so your rude speculations about my intents/skills and safety precautions, are baseless.
So if you you don't wish to offer any help regarding the subject of the thread, I sincerely ask you to refrain yourself, and most optimally- not to address me at all.

entropy51 - 3-2-2011 at 15:36

Quote: Originally posted by Mixell  
And finally, blogfast, I do not know you, and you do not know me, so your rude speculations about my intents/skills and safety precautions, are baseless.

No speculation necessary, there is data:
Quote: Originally posted by Mixell  
I think Israel is quite good for this purpose.
I can go and buy various chemicals like concentrated acids, nitrates and a lot of other stuff (and I'm 17 year old).
And no body really cares what you are doing, unless it directly harms other people.
I once rode a bus with a few litters of acids, a few kg of glassware and a few kg of reagents, and nobody said a thing.
the bus driver even waited in patience while I unloaded a big cardboard box full of dangerous chemicals.


[Edited on 4-2-2011 by entropy51]

woelen - 3-2-2011 at 23:38

I actually do not really expect any reaction between KMnO4 and 65% HNO3. Some KMnO4 may dissolve, giving a deep purple solution. Both are strong oxidizers and they do not react with each other.

Only at very high concentration, the permanganate may be (partially) converted to Mn2O7. If that occurs, then your mix may evolve gas slowly (oxygen is produced and MnO2 is left behind), but I have doubts whether this will happen at 65 to 70% concentration of the acid. It does happen with 96% H2SO4, but not anymore with 60% H2SO4 (I tried that some time ago).

What color did your liquid obtain?

It might be an interesting experiment to add a TINY quantity of funing HNO3 (90+ %) to a TINY amount of solid KMnO4. You might get Mn2O7 in that case.

Formatik - 4-2-2011 at 11:34

Quote: Originally posted by woelen  
It might be an interesting experiment to add a TINY quantity of funing HNO3 (90+ %) to a TINY amount of solid KMnO4. You might get Mn2O7 in that case.


No, it doesn't form. I've mixed those several times. Dehydrating acids and compounds like conc. HClO4 or trifluoroacetic anhydride after standing some time with KMnO4 do form Mn2O7. I've mentioned results of mixing conc. HClO4 with KMnO4 in the permanganates thread. Conc. H2SO4 is the better dehydrating agent and forms Mn2O7 right away. Nitric acid has no dehydrating action.

I've mixed KMnO4 with strong red fuming nitric acid (d= 1.52g/cc) and saw no reaction. The permanganate turned the fumes white, and that's it. Addition of some permanganate to red fuming nitric acid in Bretherick's has been said to make aliphatic alcohols hypergolic with the fuming acid. This indeed forms a strong oxidizing mixture, I've added a drop of turpentine to some of the same fuming acid containing some KMnO4 and a flame shot out.

If mixing fuming nitric acid and KMnO4 represents an explosion risk, I would expect it in the form of undiluted permanganic acid. I'm not sure about this forming so readily though. I should have had an explosion. And HMnO4 is crystalline. Even though it reacts as violently as the anhydride, permanganic acid at least as dangerous than the anhydride and decomposes rapidly and usually explosively above 3 C in the isolated, pure state. The dihydrate is also dangerous but not as severe. There is some information on HMnO4 properties in the file attached below.

Permanganyl chloride, sulfate, and moreover especially the fluoride are considerable explosion risks. But, a permanganyl nitrate is not known.

Gas evolution of mixing permanganate and nitric acid could be explained by oxygen from decomposing HMnO4. The wooden splint test would help confirm it. IMHO, I don't expect aq. nitric acid and permanganate to be any severe risk, and doubt fuming nitric acid mixed with the same also constitutes any explosion risk, especially mixed-in, in smaller amounts and uncapped.

Attachment: HMnO4 - JACS 1969, 91, 6201.pdf (263kB)
This file has been downloaded 711 times

Mixell - 5-2-2011 at 04:05

Well, the only data that you have is that I do posses some amount of dangerous chemicals (and I assume most of you are no different). Also disregarding the fact that this post was written with a humorous tone...

And back to the topic, the evolved liquid was black, probably because of MnO2 that was a product of the decomposition of permanganic acid: 4HMnO4--> 2H2O + 4MnO2 + 3O2.

So the final products were KNO3 and MnO2, not very useful...

entropy51 - 5-2-2011 at 07:11

Quote: Originally posted by Mixell  
Well, the only data that you have is that I do posses some amount of dangerous chemicals (and I assume most of you are no different). Also disregarding the fact that this post was written with a humorous tone...
The tone here is disingenuous. You stated that you transported liter and kg amounts of dangerous chemicals by public bus. Apparently all in a big cardboard box. Irresponsible and probably illegal. That is the data.

Now that we have clarified that, feel free to change the subject.

Mixell - 6-2-2011 at 11:38

I seriously don't see the problem here, the cardboard box was strengthened with duck tape, so there wasn't any chance of rupture. And everything was done in the boundaries of law.
Nothing more to say.

bfesser - 6-2-2011 at 17:14

Perhaps continue the argument via private messages?

entropy51 - 6-2-2011 at 18:16

:P