Make Sulfuric Acid (Copper Sulfate Electrochemical Method)

Make Sulfuric Acid (Copper Sulfate Electrochemical Method)


Greetings fellow nerds. In a previous video I made sulfuric acid using a complicated sulfur dioxide and oxidizing liquid setup. While pretty quick it was a little difficult to build. Then in another video I showed how to convert sulfuric acid into copper sulfate. But copper sulfate can easily be purchased in large quantities. So the question is can copper sulfate be converted back into copper metal and sulfuric acid? It can, and in this video we’ll show how to do that based on electrochemistry. First we’ll need the carbon electrodes we obtained previously from batteries. Attach and tape-on a wire to the top of the electrode so you can connect it to a power source. Now make a solution of copper sulfate, the stronger the better, and place in the bottom a copper electrode. Attach the copper electrode to the negative terminal of your battery or power supply. Attach the carbon electrode to the positive terminal and suspend it above the copper electrode. The electric current causes the copper ions to deposit out as copper metal at the copper electrode. The water is split at the carbon electrode liberating oxygen that bubbles out. The leftover hydrogen ions combine with the left over sulfate to form sulfuric acid. I’m using a six volt battery but a better method is if you can use a power supply to adjust the current and find a current level that minimizes erosion of the carbon electrode. As you can see here the carbon electrode is eroding terribly and filling the solution with particles. The length of time for conversion depends on the current applied, the coulombic efficiency, and the moles of copper sulfate in the solution. Anyway, after about an hour, I stopped mine and the next step is to filter out the suspended particles. As you can see here I stopped it short so it’s not fully converted. It will have to be put back through the cycle until it’s clear. While that’s going I’m going make another batch but this time using a much better platinum electrode. OK it’s actually a platinum coated titanium electrode but it’s still the platinum that’s doing all the work. Once again we insert the electrodes into a copper sulfate solution with the platinum electrode on top with a positive power connection. And the copper electrode at the bottom with a negative power connection. Turning on the current now. Since the platinum dissolves extremely slowly we can actually see the chemistry in progress. The blue copper ions are being plated out the solution and onto the copper electrode as a mass of spongy copper. The solution is getting lighter as it’s convert to sulfuric acid. Now before you ask, these two electrodes are the best electrodes for this process and other electrodes work terribly. In fact many of them won’t produce any acid at all. You can try them but it’ll probably fail horribly. Now I’m told a lead dioxide anodes also work but I haven’t yet made one at the time I made this video. Anyway, the conversion is now done. As you can see, we now have a solution of clear dilute sulfuric acid with bits of copper. Just filter off the copper and similar to our previous video boil down the dilute acid to concentrate it. It can be tested by mixing with sugar and seeing if it turns to carbon. So there we made sulfuric acid by using a copper sulfate solution and electrochemistry. Although it’s alot slower, it’s alot easier to do than the metabisulfite method. We’ll continue to explore other ways of making sulfuric acid in upcoming videos. So please subscribe, rate and comment.

100 Comments

  1. Hi,
    is it possible to use hard drive plates (which are platinum coated) instead of the platinum electrode you have?

  2. I'm trying something real quick, electrolysis of H2O2 + elemental Sulfur. The Hydrogen might react with the Sulfur directly in solution but it might use up all the available Oxygen quicker than Hydrogen.

  3. this is really important.. i had done an experement where i took copper carbonate ( light greensh powder and placed it in, car metel prep solution ( maybe phosphuric acid and ditergents) heated the test tube with a torch. after 2 min it boiled and then there was a blue solution ( cu2+ ions?) and a upper layer (ditergents ? ) . then i placed a bolt in the tube after cooling and copper flakes grew from the bolt. can you create a video or explain what is happening?

  4. Hey I'm fairly new to electro chemistry and really want to make sulfuric acid this way also I was just wondering can I use a piece of copper wire as an electrode or what can be used as copper electrode? would it still be possible to get excess copper in the first method? If anyone can help with these questions that would be greatly appreciated thanks.

  5. ok so I've done the test got the clear copper sulfate solution from zink.. tested the PH with litmus paper.. turns out it was water.. LOL 

  6. I got my anode in today,   I tried the carbon anode a few weeks ago and it worked.

    Got it wired to an atx power supply's 5 volt rail rated for 22 amps  and its working nicely.

  7. Three questions:
    1. Can I do this with Zinc Sulfate?
    2. Can I just bind together some pencil leads and tape them to a wire and still call it a carbon electrode? Edit: Yes–I tried it and it worked.
    3. Could I do the same thing with a nine-volt battery? Edit: Yes–I tried it and it worked. The carbon is not eroding at all 🙂

  8. for any one wondering Lead dioxide anodes can be used , it works just as effectively and doesn't degrade at all.

  9. I am trying this experiment and the reaction is near the end, but it still has a pale blue color. When the electrodes are active I think that they are splitting the water into H2 and O2 rather that reducing the Cu atoms and oxidizing the SO4 ions. Should I just let it keep going or what should I do?

  10. If anyone wonders I just calculated that 750 grams of cupper sulfate pentahydrate should give a theoretical yeld of 161 ml of concentrated sulfuric acid. Just saying…

  11. how to make concentration sulfuric acid:
    call auto supply store
    order/pay for battery acid
    boil to desired concentration
    profit???

  12. Is it possible to concentrate sulfuric acid by electrolysis? I mean sulfuric acid acts like electrolyte, and water is converted into oxygen and hydrogen? Am I wrong?

  13. Does anyone know what you would get from heating copper carbonate until it changes color to a grayish black color then adding magnesium sulfate+Isopropyl alcohol+ammonia? it's a dark blue with a purple tint and it had a white powder at the bottom, it didn't change color until I added ammonia. I am trying to make copper sulfate without sulfuric acid, any help would be appreciated.

  14. Nurdrage,
    I tried this with a Carbon electrode from a AA carbon zinc battery which was quite small. I kept the electrode at the positive terminal and the copper electrode at the negative. The amount of electricity used was 3 volts. But still the carbon was eroding slowly and it did not convert to sulfuric acid. Could u please help me out?

  15. I made the experiment using copper as the cathode and there is no copper being plated out of the solution, did I make any mistake?

  16. NurdRage, what's the hydrogen reduction potential on a copper cathode in sulfuric acid? I'm having some trouble locating that information online.

  17. I have tested this with graphite and copper electrodes.
    The solution became colorless, and I filtered it.
    Then I tried to concentrate on, I never reached the point where the sulfuric acid will fume.
    I do not think I have succeeded, what could have gone wrong?

  18. Really nice! I tried this one and it worked well – then I simply used a ceramic pot on the stove to boil away most of the water. The problem is as described to find a good electrode for the anode – even carbon rods rapidly get pulverized into particles so fine it's hard to filter out (perhaps easier if using something better than coffee filters). As the water is boiled off – even the dirt gets concentrated and the finished acid will end up rather dirty.
    Although the corrosion of the anode does not seem to be affected very much by the current. Of course – for example twice the current cause it to erode away twice as fast. But the conversion from copper sulfate to sulfuric acid also goes at twice the speed (so electrode consumption is not higher). It does however, corrode faster and faster as the process go on – the acid seems to have worse effect on a carbon electrode, than the sulphate. I did put a coffee filter over the electrode during the process – that collected most of the carbon particles and maked the sulotion stay clear enough to watch the process going without the need to stop and filter out carbon residue, all the time.
    Same thing seems to apply to the hydrogen production. The amount of energy wasted on hydrogen production is determined by the ratio between copper sulphate left and already reacted acid. There is no hydrogen being produced at start – then it start's bubbling more and more at the cathode as the reaction goes on.
    Only thing that happens if you turn down the current once the bubbles start coming is that you slow down the reaction so much that you don't notice the bubbles any more (but the same amount of hydrogen is still produced – just at a slower rate). After a while, it starts bubbling again – and you turn down the current even more. That happened to mee. I was starting at about 5 amps, then gradually dropped down to 1 amp during 12 hours. After that – the sulotion was still slightly blue and some bubbles where coming from the cathode anyway.
    Then I turned the current up to about 10 Amps, just to see what happens and there was a lot hydrogen fizzing from the anode, but it went clear in a little over 1 hour – and the electrode didnt corrode faster than it did with 2 amps during 5 hours.

    According to my other experiences with electrolyzis as well (I have made hydrogen/oxygen production and iron oxide production) – the speed of the process is directly set by the current. Current density doesn't effect the speed of the reaction – but it do affect the efficiancy and shud be kept as low as possible. Bigger electrode surface area allow for that, and put them closer together decreases resistance. The thing is that the voltage that needs to be applied to get the desired current shud be as low as possible. Every volt above the minimum needed to keep reaction going is just a waste of energy. It doesn't speed up the process – that energy is just turned to heat.

  19. @nurdrage I covered my graphite electrode with filter paper (2 layers, wrapped around) and prevented the C particles contaminating the product. Thanks for this video; I've now reclaimed my excess CuSO4 and have smelted the Cu 🙂

  20. Im stuck with carbon electrodes but I do not like the eroding. Could I possibly wrap the carbon electrode in a tissue or some membrane to prevent the spread of the carbon particles?

  21. Can this be used for other acids like nitric acid or hydrochloric acid as well ?
    using the corresponding salts of course

  22. I'm recreating this method at the moment but the electrolysis stops after e few minutes because the copper cable gets coated in a layer of a pale red substance  (I would assume it's copper oxide) how could this happen? I'm using a normal copper cable on the negative electrode and a graphite electrode as the positive one with a 9V battery (it's quite high but it started out quite good ..) Thanks in advance for an answer 🙂

  23. @nurdrage i use the carbon electrode and copper electrode connect to a 12V adapter into the CuSO4 solution but nothing happens

  24. Silly question, if you were to use a strip of lead as the anode would the lead oxidise to lead dioxide on the surface and give you an ideal anode or would you need to coat something else with lead dioxide?

  25. while doing this experimente my solution heated a bit when it became opaque due to carbon particles . Anybody knows why ??

  26. Ok. questions. Could you use a gold electrode instead of platnium? Is it possible to make nitric acid using sulphiric acid and copper nitrate? And if so, is it possible, with the addition of electricity to create a cycle between nitric acid, sulphiric acid, and the element copper that never ends?

  27. As for platinum plated titanium electrode being the most efficient, how about using a MMO electrode instead? Would it also erode fast?

  28. Yeah look I'm not being a Debbie downer, the channel is awesome and huge props for that, but the amount of sulphuric you can make here isn't enough to even warrant this particular video existing

  29. This gave me an idea to use gypsum (reclaimed drywall), CaSO4, to make CuSO4, then make H2SO4 using copper as an intermediary. It may be too slow, but hopefully the low-solubility Ca(2+) would go into solution as needed.

    First, in the electrolysis cell, anodize the copper:
    CaSO4 + Cu + 2 H2O –> CuSO4 + Ca(OH)2 + H2

    Then I suppose heat it to 100 °C to precipitate the Ca(OH)2 and filter it out (so that it doesn't react later with the H2SO4 to make gypsum).

    Then plate-out the copper:
    CuSO4 + H2O –> H2SO4 + Cu + 1/2 O2

    The above 2 reactions overall:
    2 H2O –> 4 H(+) + 2 OH(-)
    Ca(2+)SO4(2-) + 4 H(+) + 2 OH(-) –> Ca(OH)2 + H2(2+)SO4(2-)

    overall: CaSO4 + 3 H2O –> H2SO4 + Ca(OH)2 + H2 + 1/2 O2

  30. heRe questions:
    1. Can I do this with Zinc Sulfate?
    2. Can I just bind together some pencil leads and tape them to a wire and still call it a carbon electrode? Edit: Yes–I tried it and it worked.
    3. Could I do the same thing with a nine-volt battery? Edit: Yes–I tried it and it worked. The carbon is not eroding at all 🙂

  31. I found that a lead metal strip seems to work pretty well for an anode. The surface just oxidizes to PbO2 and keeps liberating oxygen without corrosion. A cheap alternative if you can't get platinum or don't want to take apart a battery.

  32. Oh there is another thing, the copper would only re-dissolve if the copper was oxidized, other wise nothing would happen.

  33. My platinum coated titanium anode turned dark brown, but it's still conducting electricity like new and haven't lost mass or become thinner. Anyone else had this happen?

  34. I suggest that it will be really cool if you will make the video about obtaining a pure crystals of peroxomonosulfuric acid!I have made some by myself and should say that it is more useful than any other chemical in the world(except nitric acid and sodium hydroxide) at least for dealing with e-waste!And it is the perfect oxidizer for making advanced propellents!

  35. I make 99% sulfuric acid with supra saturated copper sulfate solution
    Indication:
    1 for first 15-30 min. I use carbon rod from batery ( just heavy duty) i filter it and i put the semi acid (is 50-70% purity ) again but with carbon rod from pencil for super purity (90-99% purity)
    This is with a 25v with apx. 1-2amps it vorcks with 6-12v good .

  36. Now This is awesomeness, I'm guessing I can recover the Acid from sodium sulfate reaction, and because if you use graphite anodes in a membrane you will exfoliate to yield graphene as a co-product! (If you're into that sort of thing). Would it make sense to use a hot solution increasing solubility and therefore purity?

  37. How can the carbon anode be inert when it clearly is seen to breakdown? It must be taking part in the process or something at least in the carbon electrode is taking part in the process.

  38. Hey Nurdrage. I have liked and subscribed you now in turn, you have to subscribe and like this video – 'How to make Carbonic Acid [Easy Method] and also other videos of that channel

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