In an attempt to clean drain cleaner, I reacted it with Sodium percarbonate to clean up some hardware store variety sulphuric acid.

At first the reaction appeared successful, yielding a Nice Clear Syrupy sulfuric acid with a heavy crystallization at the bottom of the flask, but I don't think the salt that I collected is sodium sulfate.

The crystals are very long resembling fiberglass and based on images I've seen online, sodium sulfate's structure seems to be a lot like sodium chloride.

I'm not sure of the conjugate base formed during the reaction ($\ce{SO4-, SO5- or HSO4-}$) can anyone explain?


I've since learned that when basic sodium is reacted with $\ce{H2SO4}$ in a ratio favoring $\ce{H2SO4}$, the conjugate base produced is $\ce{HSO4-}$

  • $\begingroup$ RE: "I thought to use Sodium percarbonate to clean up.." Do you mean that you used sodium sulfate? $\endgroup$ – MaxW Nov 4 '18 at 18:57
  • $\begingroup$ @MaxW , Νο, Ι meant exactly what I said. I reacted Sodium Percarbonate with an excess of Sulfuric Acid to yield Sodium Sulfate and Caro's Acid (which I believe eventually becomes H2SO4), but the collected salt doesn't resemble sodium sulfate. It actually looks like if I crushed it, it'd be like monosodium glutamate. $\endgroup$ – user14828 Nov 5 '18 at 0:43

Ok, let’s take it one step at a time: Percarbonate is actually not a single molecule, but a double-salt of sodium carbonate and hydrogen peroxide. The sodium carbonate reacts with sulfuric acid, resulting in carbon dioxide, sodium sulfate and water. The reaction scheme is: Na2CO3 + H2SO4 -> Na2SO4 + H2O + CO2

For safety reasons I will strongly discourage you from adding carbonate to concentrated sulfuric acid. It will most likely explode in your face!

But in theory, after having added sufficiently carbonate, Sodium sulfate will precipitate. But getting a drying effect will be uphill, since water is produced alongside the sulfate, as you can see in the reaction scheme, on top of this is any water that comes from hydrogen peroxide, not to mention the fact that concentrated sulfuric acid is strongly hygroscopic itself. As for the cleaning of impurities, I fail to see what neither carbonate nor hydrogen peroxide can do. HP can oxidize some organic materials, but most of these will probably already have been destroyed by the sulfuric acid. It can also oxidize some inorganic ions like sulfite (SO3), but do you suspect these to be a problem? I don’t have detailed knowledge of the conditions needed to form peroxo(mono)sulfuric acid. Undoubtedly some will be formed when HP is added to sulfuric acid, but I am also convinced that only a fraction of the sulfuric acid/HP will react.

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  • $\begingroup$ Since I asked that question I've learned quite a bit. It actually produce peroxymonosulfuric acid and did purify the acid to complete clarity, however there was a prohibitive amount of acid lost to Na2S04 production, not to mention the amount lost during filtration, then there was the issue of water that had to be boiled off which lead to the precipitation of the rest of the sodium sulfate. From what I understand at the ratio used, reacted the sodium percarbonate with the sulfuric acid to yield sodium bisulfate? I'm new at chemistry. I just learned to balance equations properly. $\endgroup$ – user14828 Dec 1 '18 at 10:52
  • $\begingroup$ $\ce{SO3-}$?, because the way you phrased it, you look like you're talking about sulfur trioxide and not the sulfite ion. Percarbonate doesn't explode in your face unless you react it all together suddenly, like a dimwit. $\endgroup$ – user14828 Feb 24 '19 at 8:18

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