suylfuric acid stuff

[collector]

By destilling HClO4 you end up with an azeotrope containing ~70% HClO4. Removing water from this is not easy. And highly dangerous.

One way of producing water free HClO4 is by treating solid KClO4 with conc H2SO4. Then you get HClO4, no water content. This is not the same as the azeotrope ~70% HClO4. And certainly not the same as chlorine (VII) oxide Cl2O7.

 

It is a completely different fact that Cl2O7 react with water, producing HClO4. "Cl2O7+H2O-->2HClO4. Cl2O7 is perchloric anhydride"

Yes, but this does not mean that HClO4 and Cl2O7 is the same thing.

 

SO3 reacts with water, producing H2SO4. But no one would say that sulfur trioxide (sulfuric acid anhydride) is the same thing as sulfuric acid.

Or that phosphorus pentoxide is the same thing as phosphoric acid.

Etc.

[budullewraagh]

when you react conc H2SO4 with KClO4 you get Cl2O7, NOT HClO4. SO3+H2O-->H2SO4, yes, but at high concs, what are those fumes? SO3, NOT H2SO4.

[woelen]

chlorine (VII) oxide' date=' Cl2O7 and anhydrous perchloric acid are exactly the same.

 

and yeah, heat it or hit it with a hammer and it will decompose. but im talking about storage. if it's stored properly, it shouldnt be problematic.[/quote']

Just stay away from Mn2O7. I once made this with a few mm3 of KMnO4 and a drop of H2SO4. I saw a faint violet vapor (it is volatile) and every second or two a tiny speck of light (these were dust particles from the dust of my room, touching the liquid and oxidized immediately). After a few seconds it suddenly went BOOM and I had many tiny brown droplets on the wall and on the table, on which I did the experiment.

[Etacude]

I remember in my secondary school I have made this stuff. I added small amount of conc sulphuric acid to potassium permangante crystal to make a paste. Use a glass rod and collect some of the stuff at one end of the rod. Then gently transfer over to the wick of a spirit burner that prefilled with ethanol. The moment the paste touched the wick the flame just automatically lights up!

 

Luckily I never experienced any explosion though.

 

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