Making Sulfuric Acid

Making a small sample of sulfuric acid by the electrolysis of copper sulfate.

[@ScrapScience]

Hello everyone! As you might note, this is an extremely old video (the second oldest on my channel, I think). Now that I know a little more about what I'm doing, I'd like to point out that if you're actually going to try this yourself, please avoid using a lead anode. Lead poisoning from mishandling or the resulting soluble lead is always a good thing to try to avoid. I strongly recommend using graphite instead - a much safer alternative.

[@ZoonCrypticon]

Could you use titanium oxide instead as an electric conductive anode, that wouldn´t be poisonous ?

[@ScrapScience]

@ZoonCrypticon Titanium dioxide isn’t conductive, so I’m afraid not.

[@hamzashaheen3581]

Also The Sulfuric Acid Particles That Will Be Emitted When The Gas Is Bubbling out Is Carcinogenic In Long-Term Exposure

[@joem.8198]

I used a graphite anode and I didn't even have to filter black carbon residue out of the acid. It all just settled at the bottom along with the copper. Keep it up Scrap Science! I enjoy watching your chemistry videos.

[@kreynolds1123]

My local hardware store has sulfuric acid. But I live in the US with much less nanny regulation. But great Job! Knowledge is great to share, and thank you for the equasions.

[@GRBtutorials]

But at which concentration? And is it impure drain cleaner?

[@firstmkb]

30% and yes, it has additives suitable for a drain cleaner. You can also purchase it online at higher strength, and a much higher cost, for example plus $100 hazmat (hazardous material) shipping fee.

[@kreynolds1123]

@@firstmkb kzbin.info/www/bejne/anW4eIWNn8mBgqs does a great video on this.

[@chemistryofquestionablequa6252]

@@firstmkb we have drain cleaner that's 98%, costs about ten dollars, has pink dye, but it's never interfered with a reaction I've used it for.

[@leeroy144]

There are a few kinds that are 98% with no additives. I get liquid lightning the one that says "virgin sulfuric acid", they also make some with a buffer in it that makes it brownish. But mine is completely clear. There are a few other brands but I don't remember their names.

[@nunyabisnass1141]

If using a carbon rod, one may use a sleeze of some kind that will catch the fine particles, allow current to pass, and is resistant to the acid. If i recall, tea bags are made of cellulose, so as long as neither the temp nor concentraton gets too high, it should work.

[@vr7861]

I really liked your detailed yet accessible explanation of the electrolysis goin on in this reaction. Big fan of the low-tech diagrams (i.e. no flashy graphics or terribly scribbled blackboard/whiteboard drawings)

[@John-un3lj]

Forbidden Gatorade right there. Very nice.

[@guythat779]

I really love your detailed explanation Electrolysis is a lot of info to juggle in your head so seeing it visually represented somehow is great

[@lukehanlon9965]

Fantastic video Mate!! Thank you. if you use the carbon electrode option, then collect the black sludge and make nitric acid with the sulfuric acid and a nitrate of your choice, then intercollate the graphite sludge with a mixture of sulfuric and nitric acid and then sonicate it in a sonic cleaner bath you will then be the proud owner of some Graphine!!

[@guythat779]

Graphine?

[@guythat779]

@Polish Chemist I think man's a few steps ahead of us indeed

[@Swagnermite]

Great video!

[@ElectraFlarefire]

I was looking for this video but didn't know it.. I was getting ready to do nurdrage's electrobromide method, but this is so much easier! Thank you.

[@sciencefusion5352]

And i was looking for the perfect alternative for platinum electrode but i m still thinking will the lead dioxide anode last long 🤔🤔🤔

[@loganbrown9553]

@@sciencefusion5352 lead electrodes are not great because you risk lead contamination which if your not prepared to deal with is a pretty big hazard. By far the easiest, cheapest, and safest anode is graphite as its resistant to oxidation and arent toxic. While the carbon powder in annoying it can be filtered out and won't spead lead everywhere you use the sulphuric acid.

[@sciencefusion5352]

frnd i used lead bar and it worked very well and awesome the result are satisfactory i am getting hundred ml of concentrated sulfuric acid from one pound of copper sulphate pentahydrate the reaction is occurring very fast as I am using large lead bar with high surface area I live in India and for me lead metal is much cheaper than carbon rod 😁 thank you Thank you again ☺️

[@jeffholmes1362]

Brilliant, I’ve been needing sulfuric to treat my andamooka matrix opal. This is a great solution to my problem. Thanks for sharing

[@superdave54811]

Good to learn. Thanks.

[@johanson321]

Wow nice experiment with calculations! We'll try this today in chemistry out here in San Diego:) I think we will try using steel wool as our cathode!

[@peterbranton6845]

I just learnt so much thank you very much

[@also5159]

I love this equation of redox reations and explaination

[@franciscoparraguez4576]

Thank you so much !!!!! 👏👏👏👏👏👏👏

[@peterbranton6845]

Hi mate, thanks for the vids , I made some, I used the magnesium sulphate method and the ammonia sulphate method. I’ve got a digital ph measure, after many hours I tested the ph the lowest ph I could achieve is 1.4, I needed it to react with sugar so I needed it to be stronger. I looked up the distilled method but it requires speacialist equipment etc, but then I thought unlike distilling alcohol this time I’m trying to separate the lighter ingredient that has I lower boiling point “water” so I bought a cheap Pyrex jug and placed it on a inverted clothes iron for 12 hours after which the liquid has been reduced, at no point did I boil the liquid, the end result gave me a acid with 0.2 ph ! I’m very pleased with that, I’ve yet to try it with sugar but I intend on doing so as soon as I return home from work , thought you’d like the feed back, cheers

[@guythat779]

Wonderful! Did it work?

[@willowpine2604]

You can increase the % of h2so4 by refill the already solution with cooper sulphate and remake electrolysis again! Nice video thumps up!!!

[@mostaprsio4497]

that's amazing result is totally pure H2SO4 keep going brother

[@islandblind]

To find sulfuric acid, go to a store that caters to the janitorial trade. They often sell sulfuric acid in concentrated form as a drain opener, at least here in Canada.

[@sharkiverse]

Indeed, just the other day I went to a home hardware in Ontario and found a bottle of sulfuric acid drain opener that claims to be 96%, it does have some dye it in though so it may be necessary to break it down with some hydrogen peroxide.

[@gresmaster2279]

Well the problem with that is that i live in Europe, here the regulations are a lot stricter than in America so u can't get sulfuric acid that way.

[@firstmkb]

Thanks for going through the math! Where did you get the oxidation and reduction voltages you showed for the preferred reactions, and how would you calculate when one becomes preferred at different concentrations (e.g. Hydrogen versus copper)? Great videos, thanks for sharing!

[@ScrapScience]

Wikipedia has a data page of standard electrode potentials which I used for this reaction, and a bunch of online textbooks and pages have similar information. As for calculating the potentials at different concentrations, you need to use something called the 'Nernst equation', which is a little too complex to explain in a youtube comment, but it basically allows for calculation of a reduction or oxidation potential at different concentrations/temperatures/pressures. There are a bunch of websites online that explain it better than I ever could, so if you're interested, I'd recommend just googling it.

[@firstmkb]

Scrap Science thanks! Having the name of the equation is a huge help, as is the phrase "standard electrode potentials."

[@oneproudbrowncoat]

@@ScrapScience Out of curiosity, how would tungsten compare to the graphite?

[@willowpine2604]

​@@ScrapScience if you refill the solution with CuSo2 powder and continue to make electrolysis will that gives you more concentrated sulphuric acid??

[@peterbranton6845]

After heating it again in a Pyrex jug on a inverted clothes iron I’ve reduced the liquid to 50 ml from original 330ml I’ve had to filter it to remove some salts that had formed, the result is a liquid with a very slight blue tint measuring 0.3 ph at 18 degrees C

[@petrlaskevic1948]

Verz nice! How did you remove the salts?

[@peterbranton6845]

@@petrlaskevic1948 I didn't

[@petrlaskevic1948]

@@peterbranton6845 You said you filtered them

[@pavithrank1012]

After getting clear solution of H2SO4 and then add CuSO4 again then eletrolise the solution again. Would the concentration of sulphuric acid increase.

[@ScrapScience]

Yep, it certainly would, just be aware that the solubility of copper sulfate will decrease as the concentration of sulfuric acid rises.

[@Telectronics]

@@ScrapScience Does that mean you won´t be able to get to 96% alone by electrolysis ? If not I heared heating down the volume should help is that right ?

[@ScrapScience]

@Telectronics Yep, while you can achieve pretty high concentrations with this method (I've achieved as high as 40% in the past, and it could probably go higher), electrolysis alone will struggle to generate concentrations over 50-70%. While it would in theory be possible to get closer to 90%, the low solubility of CuSO4 and the drastically decreased conductivity of the sulfuric acid (which occurs at high concentrations) makes this a very slow and inefficient process. On top of this, very concentrated sulfuric may start to react preferentially on the anode, contaminating the sample with peroxydisulfate. It's much more sensible to make some reasonably concentrated acid by this method (25-45%) and then boil it down or distil to concentrate. Not that that's an easy thing to do, boiling acid is something to be done only with proper safety equipment and quality glassware.

[@Telectronics]

Yes you are right it´s dangerous enough when it´s cold but hot even more. Destilling should at least avoid splashes and fumes are directable which could be saver. Thank you for your detailed answer. I appreciate it you do always a great work :)

[@adamcoogan9122]

I’m trying to get my head around the calculations and have rewatched the 7:57 part numerous times. When working out the moles of H2SO4 in 200ml of water where do you get the 5 figure from for 0.06 mol x 5 = 0.3M

[@ScrapScience]

The 5 figure comes from the reciprocal of the volume in litres. I'm skipping a step in there, but: concentration = moles x (1/volume). I'm finding the concentration by multiplying moles (0.06) by 1/volume (1/0.2, which is equivalent to 5).

[@adamcoogan9122]

Scrap Science thanks so much 💡 now it makes sense.

[@lioncub1257]

I use a lead anode, basically a long wedge sinker.. First ran it at around 300mA till it was black then around 3 amp and later 5 to 7. Seems to be holding up very well no signs of breaking up or going into solution. I notice that when the CuSO4 concentration was high strong strong copper trees formed but now that is had finally became pale blue the copper is spongy and now gas bubbling from both copper cathode and lead anode. What happens if one continuous too long will the water start to be electrolyzed and will this in fact increase the acid concentration? If one stops and there is still a very pale blue color how to remove this?

[@ScrapScience]

First of all, please be careful if you use a lead anode, lead dioxide is inherently incredibly toxic and improper handling can lead to serious life-lasting health effects. Just make sure nothing gets contaminated with lead salts and/or make sure to cathodically convert the lead dioxide back to lead metal after you're done. As you saw, towards the end of the electrolysis you'll get an increasingly weak CuSO4 solution, and as this happens, water does begin to become electrolysed. The rate of this is relatively negligible though (at 1 amp you'll split about 0.3mL per hour), so it's not a concern for any change in concentration. The only real way to remove 100% of the CuSO4 is to continue electrolysing until its all gone. It might seem like it takes a long time to remove, but eventually it does disappear.

[@philipvernejules9926]

.......yes, that very fine brown lead dioxide is insidious. I don't trust it drifting about in household dust . It gets deep into the latex gloves and surely is nano particle level dust.

[@Mark6E]

Hello, I have been trying this with a very similar setup other than I am using carbon motor brushes as my anode, I have tried lead sheet with the same result. 50g of CuSO4 in 150ml solution. I intend to use the acid for anodising small aluminium parts. I notice that the anode gas/steam does not appear to increase the flammability of lit tissue paper and has a slight odur, changes a flame colour green, making me question which gas is generated and if it contains copper? I have stopped for now incase I have something wrong. Copper has grown around the cathode so that part is working. Any ideas? Thanks

[@ScrapScience]

You've done everything correctly, there's no need to worry. The amount of oxygen gas you generate on the anode is, in general, not produced at a rate high enough to make anything burn faster. Also, the green flame is due to the fact that when the oxygen bubbles burst at the surface of the solution, they aerosolise a small amount of copper sulfate solution, which gives you a strong green flame even when you have tiny amounts. I'd definitely recommend sticking with carbon electrodes as well. Despite the erosion you get, it's much nicer than having to deal with the toxic lead oxides that form on a lead anode.

[@pissedofffrog6778]

Would a few batteries work to generate the current needed instead of whatever generator setup he has going on there?

[@ScrapScience]

It would work, but batteries would run out very quickly when used in these kinds of processes.

[@NishchayG]

i have pure PbO2 rod, can you say me a way to use it. as it will not conduct electricity now

[@ScrapScience]

It really depends on how you got the lead dioxide, if you bought the PbO2 anode online, then your electrode is probably dead and unusable. If you made the lead dioxide from lead metal, I would seriously recommend converting it back to the metallic form (by using it as a cathode in a sodium carbonate electrolyte for about a day) as the PbO2 form is inherently VERY toxic and is difficult to handle safely. Using PbO2 anodes, especially ones made by anodising lead, cannot be used for pretty much any reactions besides the one shown in this video and simple water electrolysis of sulfuric acid. I would encourage the use of graphite anodes rather than PbO2 in any electrochemical reaction unless you have the proper safety equipment to deal with lead compounds.

[@mrdojob]

@@ScrapScience Would it be a good idea to bake the copper sulphate to get rid of the water already in it as it always seems to come in a saturated form? Seeing that water is the most annoying contaminant in acid it seems like a great way to get rid of a lot of it before even starting. The only place for the hydrogen needed to make the acid to come from is by consuming your original starting water itself. Also those lead dixoide electrodes are great. They seem so useful.

[@phonetube1279]

Another idea I thought of, but can't find much info on is burning pure sulfur in an ozone rich atmosphere and bubbling it through water or burning sulfur in normal air and bubbling it through ozoneated water. Do you think this might work?

[@ScrapScience]

I'm honestly not sure about the kinetics of the reaction between sulfur and ozone (or sulfur dioxide and ozone). It's possible that it might work, but the generation of ozone is generally an extremely inefficient process, so you'll be facing a very energy-intensive generation method.

[@unlockeduk]

was about to say to use lead as annode and then you did it lol i get good results using just lead as it will oxidise to a degree making an inert layer on the surface any way it works very well. heating untill fuming happens brings the concentration up to well over 75% or distill if you have apparatus . oh and THIS ONLY WORKS WITH DC just thought thats a point that should be obvious but ..........

[@alphabravo2181]

Will lead ingots already have a dioxide coat? Can I just use those? Should I wear gloves when handling the lead?

[@ScrapScience]

Alpha Bravo yes, you can just use lead strips or ingots as they will quickly form a dioxide layer for this reaction. If you’re going that way then you’ll definitely need to wear gloves and preferably even more safety gear, seeing as the toxicity of the lead compounds is very high. In fact, if you can, I would recommend using a graphite anode instead.

[@alphabravo2181]

Scrap Science I don’t have any graphite ones but there cheap so I might just buy one to save myself from the toxicity, I have lead and compounds of it in my room in plastic containers, thats all right for now. I’ll see if I can get some graphite

[@mummiedanser1609]

Since there was a lot of H2 that formed, wouldnt that mean that the solution is just SO4(2-) with a little bit of H+ ions? So its not really sulfuric acid or?

[@ScrapScience]

While there was a lot of H2 discharged at the cathode, especially near the end of the run, the anode reaction was actually producing H+ ions at the same rate that they were being destroyed, so the overall concentration of the H+ didn't change.

[@mummiedanser1609]

Scrap Science ohh of course thanks!

[@axeman2638]

Would the continued electrolysis once the CuSO4 is all gone concentrate the acid further?

[@ScrapScience]

Yes, but it's a lot quicker (and at least ten times more energy efficient) to just boil the water out instead.

[@axeman2638]

@@ScrapScience cheers

[@fusion5329]

What would 0.3 molar of sulfuric acid be in percentage concentration? For what i want to use it for i need it to be like at least 90% preferably. Water to Sulfuric acid ratio i am talking about. Thank you i am loving your content.

[@ScrapScience]

0.3 molar is approximately a 3% solution of sulfuric acid in terms of weight percent. If you need 90% stuff you’ll probably find it very difficult to make. Outside of high temperature distillation there’s really no practical way of making highly concentrated H2SO4. The best you could do is probably buy some drain cleaner (normally around 95%) if it’s sold in your country. Other than that you might be able to get battery acid, which is around 30%.

[@sciencefusion5352]

After electrolysing 1 pound of copper sulphate pentahydrate gives 100 ml conc 98% azeotropic sulphuric acid after boiling the solution water

[@algator55]

Copper crack pipe solution is very well known in our community it always helps us get through tough times

[@survivalbert7017]

How would you have filtered the solution? As sulfuric acid is quite corrosive, most "simple" filtering media (e.g., cotton or sand) would get destroyed and thus contaminate your acid.

[@ScrapScience]

Regular old filter paper or even a paper towel are good options, as the acid won’t react with them unless very concentrated

[@survivalbert7017]

Ah, ok - thank you! I didn't know that sulfuric acid only reacts with paper or cotton when it is in concentrated form.

[@AlanCartman]

Nice video. Can I use an anode of zinc?

[@ScrapScience]

I'm afraid not, the zinc will quickly dissolve in the sulfuric acid under anodic conditions. For the anode you're stuck with using only lead, graphite, or platinum, though when using lead you'll need to be careful of the toxicity.

[@AlanCartman]

@@ScrapScience I'm repeating it with lead with a current of 2 amp. What is the maximum current that lead can support?

[@ScrapScience]

@@AlanCartman It really depends on the surface area that you have between the electrode and the solution, but using something of similar size to the one I use in this video could easily handle about 5 amps (provided that the whole thing is submerged). If your electrode is solid lead then It'll be unlikely for you to be able to wreck it due to high currents. Be wary that the current in the cell will dramatically increase as you generate more and more sulfuric acid. Also, make sure not to touch the anode with bare hands after it's been used.

[@peterbranton6845]

Could the porous clay pot be used to protect the carbon electrode ? If the copper electrode is inside the clay pot and the copper sulphate solution is inside the clay pot , and the clay pot is then placed into a container that hold water with the carbon electrode on the outside of the clay pot but in the water , if you know what I mean ?

[@ScrapScience]

I'm afraid a diaphragm won't protect a carbon electrode from disintegrating. The acid is generated directly on the carbon electrode, so the product will inevitably fill with carbon dust unless you use a different type of anode.

[@donaldsmith3048]

Can you trap the hydrogen gas and the oxygen gas to use later? And where is the best place to get copper sulfate? Copper wire is easy to find and so is lead! Using a much larger container and a funnel shape over each of the electrodes should trap the gas to use later. About what % is the acid? Would putting more copper sulfate in the water give a higher %of acid?

[@ScrapScience]

1) You definitely can collect the H2 and O2 gasses. However, there are much more efficient ways to do that electrolytically, and the amounts of gasses generated on this scale are quite small, so I don't normally bother. 2) Copper sulfate is a very common gardening supplement. I get it at my local hardware store, but nurseries will probably also provide it too. 3) In hindsight, using lead metal as an anode here was a stupid idea. It results in contaminating the solution with a considerable amount of soluble lead, which is difficult to handle or dispose safely. A much better option is to use graphite/carbon (even pencil lead will work), though it does slowly disintegrate and you'll need to filter the final product. 4) The percentage of acid produced here is on the order of 3%, but I've since scaled up the reaction to make 40% acid with no problems. Getting anything above 70% concentration would be unlikely though, as the reaction proceeds much slower as the acid concentration rises. 5) A higher amount of copper sulfate in the initial water will generate a more concentrated acid solution, yes, as the two quantities are proportional.

[@Davidjardinssemisgreffesbonsai]

Hello, super vidéo instructive ! Ma question est la suivante : comment purifier l'acide au maximum ? Merci beaucoup et tout le meilleur pour la suite 😊

[@ScrapScience]

Distillation is the only proper way to do it. That's a very serious task though. I wouldn't recommend trying it without some serious safety knowledge and equipment.

[@Davidjardinssemisgreffesbonsai]

@@ScrapScience merci, je pensais qu'il fallait passer par une distillation ! Au vu du taux d ébullition de l'acide sulfurique il est mieux d'utiliser une pompe à vide et ajouter une colonne de vigreux changerai le résultat ? Procederiez-vous avec la pompe à vide et la colonne de vigreux ? Merci à vous

[@ScrapScience]

A vigreux column is not necessary for sulfuric acid distillation. In fact, it will significantly reduce the speed of your distillation. Distilling under vacuum would be ideal, since it will decrease the temperature required for boiling sulfuric acid (which is usually over 300 C). Once again, distillation of sulfuric acid is not a task that is easy or safe, especially when performing it under vacuum. Care and knowledge is definitely required here.

[@Davidjardinssemisgreffesbonsai]

@@ScrapScience merci, pour l'information !

[@adamrandall5163]

Can the copper metal crystals created in this be used in place of Copper Oxide in other experiments when required?

[@ScrapScience]

Nope, I'm afraid not. Copper metal is generally much less reactive than copper oxide (at least in terms of aqueous chemistry), so the properties will be different. It might be a perfectly good substitute for some (select few) reactions, but in the vast majority of cases, it won't do the same job.

[@Tunkkis]

Man, the anglosphere way of using periods as decimal separators and commas as different separators will never not be jarring to me. Very well done video, almost felt like being back in high school Ke04.

[@00bean00]

Suomelainen?

[@Tunkkis]

@@00bean00 Kyllä vaan.

[@renatoacquadro328]

hello, nice video. I'm not a chemist but I have knowledge, I dabble every now and then with something simple. I wanted to ask you for advice, first I'll explain what I did: I took HCl + CuSO4 -> H2SO4 + CuCl2 +H2O I don't balance them but it is to understand. Now I wanted to precipitate the Chlorine to separate it from the acid by adding NaCl to get (CuCl2)2NaCl which should sink to the bottom. Since it was an experiment I didn't calculate the weights of the reactants, so approximate with the concentrations. The question is why if theoretically I should have the precipitate but in practice it doesn't happen to me? I have not tried but I also thought by electrolysis to separate the copper and the chlorine should bubble from the cell. Thank you very much, if you have another method to separate the chloride to suggest it is welcome. In the past I redid the collector (covered a crack) in copper of an alternator and it came out beautiful, file hard copper with perfect crystalline structure, the trick is an lm317 and constant current and good patience for the time. Thanks a lot and congratulations.

[@ScrapScience]

I've never heard of "(CuCl2)2NaCl". Do you have a reason to believe it should produce a precipitate?

[@randallmarsh446]

could you mix a magnesium sulphate with the copper sulphate to get a greater yeild?

[@ScrapScience]

Not in this case. Magnesium sulfate will not be affected by electrolysis under these circumstances, so you'll only be converting your copper sulfate into acid.

[@EssexSilvering]

Thanks for sharing, think your videos are great! .... One question about this Sulphuric Acid, ... What percentage is this? Roughly is good enough ;-)

[@ScrapScience]

If I remember correctly, the percent concentration for this particular video was around 3%. However, I have been able to achieve a concentration greater than 20% in other experiments by simply using more copper sulfate to start with.

[@EssexSilvering]

@@ScrapScience .......... Thanks for your reply, ... So the more sulphate, the stronger the acid gets? ... I've heard that it makes no difference, but they might not know anyway! ... I was looking to try and get some up to 90% or more, .. I've also heard that if you boil the acid up it makes it stronger, is that correct? ... Cheers ;-)

[@ScrapScience]

In this case, seeing as you’re making the acid from the sulfate directly, using more sulfate will make a larger quantity (or concentration) of acid. I’m afraid you’ll struggle to get any concentration above 50% with this method, as past that point, the conductivity of the solution drops drastically and the reaction almost stops. If you want a higher concentration, you will need to boil it down, but this is incredibly dangerous and requires temperatures of over 300C. If you go that way, I’d recommend reading up on some safety procedures and using proper glassware seeing as boiling sulfuric acid is not very nice. If you’re using the method in this video, I’d also recommend using a graphite anode, to avoid the toxicity of the lead electrode.

[@mummiedanser1609]

@@ScrapScience can't you just boil off the water? Then it doesnt need to be 300C but only around 100C

[@Swagnermite]

@@mummiedanser1609 yea you can, just boil it until you see white fumes

[@chillmusic8083]

I did not understand something, how do you manage to pass 0v to the negative terminaland 12v to the positive one? please answer me i am a beginner

[@ScrapScience]

I can't quite explain the fundamentals of what 'voltage' is in a single KZbin comment, but simply, the voltage applied to a single terminal is different to the voltage difference applied across a load. Basically, you can apply a single voltage (be it 12V, 5V, 0V, -200V, etc.) to any given terminal (for example, an electrode, a piece of metal, or one of the ends of a resistor). However, when you have a load (usually between two terminals), it is the 'voltage difference' (or potential difference) between the terminals which determines how current will flow. For example, if you apply 7V to one end of a resistor, and 5V to the other end, you get a 2V potential difference across the resistor (since the difference between 7 and 5 is 2). You can then use this value in Ohm's law to predict the current flowing through the resistor. Or for another example, a standard AA battery will give you 0V on the negative terminal, and 1.5V on the positive terminal. So, when you connect this battery to a load, you'll get a 1.5V potential difference across the load. (Also note that 'zero volts' really has no definite meaning, it's only the relative differences between voltages which have any significance. You could call the negative terminal of a battery '-800V' and the positive terminal to be '-798.5V', and everything would still be exactly the same) In this case, I've just applied 0V to the cathode, and 12V to the anode, so the potential difference across the cell is 12V.

[@Chris-op7yt]

So what sulfuric acid percentage was produced this way? Or asked another way, how much extra ph 7.0 tapwater to add to make it roughly ph 5.0? looking to possibly use dilute sulfuric acid to lower the ph of my garden soil, as adding lots of expensive sulfur isnt doing much. i have highly buffered soil that i want to reduce to ph 6.0 - 6.5, which is ph 7.0. Additionally the sufuric acid should help with clay. I would only try this if i can make several watering cans of dilute ph 5.0 in one go. else it wont be worth it. good work.

[@ScrapScience]

The percentage concentration produced in this video was around 2%, or a pH of approximately 0.7. This concentration is directly dependent on how much copper sulfate you start with, so you'll need to do some stoichiometry to work it out if you're going to give it a go. If you want a pH of ~5.0, you'd need to dilute this particular solution with tap water by a factor of around 10,000 times (i.e. 1mL diluted into 10L of tap water), but again, this will depend on how much copper sulfate you started with. pH test strips will be essential here to check that you've got it right. You'll also definitely need to avoid using a lead electrode if you're using this stuff for your garden to avoid lead contamination/poisoning (use a graphite anode instead).

[@Chris-op7yt]

@@ScrapScience : thanks very much for answering. sounds like a single small batch like you did would be enough. see how my soil reacts to latest $100 worth of sulfur application. if it bounces back up again, might give sulfuric acid a try. have to wait for the applied sulfur to work. apparently some farmers use sulfuric acid from a tank and boom, to apply to farm soil. nobody's done a video of application of diluted sulfuric acid to clay soil. thanks and cheers

[@RedDogForge]

200 ml of 0.3 acid meaning what percentage strength?

[@noshyt2106]

Do you increase amps to 2amps by increasing the mass of copper sulphate?

[@ScrapScience]

I suppose, yes. You can also increase the voltage to do the same thing.

[@phonetube1279]

Can this be done with ferrous sulfate ?

[@ScrapScience]

Only partially. You might get some conversion of ferrous sulfate to sulfuric acid, but the process becomes much less efficient as the acid becomes more concentrated, so you’ll never be able to get anywhere near 100% conversion, and your product will always be very dilute and contaminated with dissolved iron ions. Additionally, the anode reaction will very likely just convert ferrous ions to ferric ions, preventing the formation of acid entirely.

[@Michy20]

Can i use a nickel silver rod instead of lead?

[@ScrapScience]

I'm afraid not, your anode will quickly deteriorate in a cell like this. I'd recommend finding some graphite electrodes (sometimes you'll find them as 'gouging rods' for welding) as they seem to be the easiest to get hold of for most people. I'd also advise against using lead anyway unless you're equipped for the toxicity.

[@giansieger8687]

couldn‘t you over-electrolyze (meaning you leave it running for a full 24 h), to start electrolyzing the water which will increase the concentration if you don‘t feel like heating a corrosive acid to 350 deg C?

[@ScrapScience]

While it would definitely work to some degree, concentrating the acid by electrolysing away the rest of the water is extremely slow, and incredibly energy intensive. To get rid of 100 mL of water, you'll need a whole kWh of electricity (at least). Additionally, once the concentration of your sulfuric acid raises above around 50%, the conductivity rapidly decreases, preventing electrolysis from occurring effectively. Overall, it's a lot more energy efficient to boil the water off (most of which can be done at near 100 C), and getting concentrated acid (where the required temperature will rise to 300 C) actually requires it.

[@phonetube1279]

Can you use the same process with magnesium sulfate ?

[@ScrapScience]

Not quite. The very low reduction potential of magnesium prevents it from plating out under aqueous conditions. You’ll just be electrolysing water in that case. Turning magnesium sulfate into sulfuric acid requires a cell with a diaphragm or a membrane. I have a video on this topic as well (‘making sulfuric acid from epsom salt’), but it is extremely inefficient and produces a low quality product compared with the copper sulfate method.

[@peterbranton6845]

Update, when I got home from work the solution had cooled to 15 c I tested the ph again and it was 0.7 so when the solution is warmer it has a lower ph why is that? I started with 330ml at 1.4 ph and reduced it to 100ml . I’m now going to try reducing it further to hopefully decrease the ph further. I’m reducing it on a heat approx 80c , I’ll let you know the results

[@jasonjohnson2813]

There is more energy in the system, allowing for more hydrogen ions to be stable in solution.

[@tahallium]

i tried this with pencil graphite but it dissolved quickly ;( any ideas? i dont like using battery graaphite rods cause i think theres toxic heavy metals in the like thallium cadmium arsic mercury... OH can i bubble h2s to make CuS and H2SO4?

[@ScrapScience]

It will really depend on the battery as to how much heavy metal contamination you'll get, 6v lantern batteries are often pretty good in that regard and contain high quality graphite rods. Toxicity is a pretty reasonable concern though, so you could also buy graphite rods online, or buy 'gouging rods/gouging carbons' from a welding supply store (they come coated in copper but that won't affect this process as the copper will dissolve off quickly under anodic conditions). Using H2S will likely work as intended, but the gas is pretty scary to work with in my opinion. If you're capable, and have the setup for making/containing H2S, go for it!

[@abdalrahman3766]

I use this method to produce sulfuric acid, but at the beginning of the analysis a light colored solid copper forms on the negative electrode, which affects the analysis. I don't know what the reason is. I have to clean the cathode every few minutes for half a day to a day, and then a soft, dark copper forms, and the analysis is successful. No, I understand why this is made of copper. Is this due to the high percentage of copper sulphate in the water? Because I dissolve one kilogram in approximately two liters of water. If you can help me, I will be grateful

[@ScrapScience]

From what it sounds like, it's likely copper hydroxide forming on the electrode because the cathode will tend to generate slightly basic conditions when you start from a neutral solution. You can probably stop this from happening by adding a small amount of previously produced sulfuric acid to the cell before you start.

[@changweihsu]

Would normal coffee filter work well on filtering the carbon? HDPE is the only plastic safe for storing sulfuric acid, right?

[@ScrapScience]

A coffee filter will work fine for any concentration you're able to generate with this method. Lots of plastics can store sulfuric acid, HDPE, PP, PE, and PET (to name a few) will all do fine at concentrations less than ~80%.

[@changweihsu]

@@ScrapScience If you keep adding copper sulfate when it is clear, would the concentration go higher and higher? Is there an upper limit to this?

[@ScrapScience]

@@changweihsu Yes, adding more copper sulfate continuously will make more acid. However, there is an upper limit in the sense that copper sulfate will become less and less soluble as the acid concentration increases, reducing the efficiency as more acid is generated. You may also run into problems of faster anode degradation at these higher concentrations too. I’d imagine a sulfuric acid concentration of 50% is probably obtainable by continually adding copper sulfate, but getting anything above ~70% would surprise me.

[@changweihsu]

@@ScrapScience Hi Harry, I was wondering if letting the water evaporate by sunlight will increase the concentration of the solution. Does it work for other acids?

[@ScrapScience]

@@changweihsu Yep, leaving it in the sun, or a warm place, will allow the water to evaporate and increase the concentration of the acid. This will become less effective as the concentration increases however, as it will gradually require more and more energy to drive off the water. This will work to some degree for most acids, particularly dilute solutions, but acids like HCl and HNO3 are somewhat volatile, and you will lose some in the process.

[@ceasargaming9041]

hey! i did this same reaction, and everything seemed to be going well, but despite copper depositing on the anode, my solution is still blue after several hours. Albeit lighter blue...but yeah. Also my solutions heats up A LOT when i run it. Any ideas?

[@ScrapScience]

Several hours is unlikely to be enough to run a reaction to completion, depending on how much copper sulfate you started with and how much current you're running. Some of my more recent runs of this reaction have taken multiple days. If your solution is heating up, it means that you're running the reaction at a voltage which is far too high. You only need a few volts, and anything above that will just lead to more heat.

[@ceasargaming9041]

@@ScrapScience ok thank you! i connected a 18V drill battery running at 4.3 Ah....not sure how much copper sulftate, as I made the solution from electroysis of magnesium suflate and a copper electrode lol

[@ScrapScience]

That'd do it! 18 volts is well above what you need. If you've got a spare phone charger lying around, those work quite well since they provide around 5 volts. And just so you're aware, Ah (amp-hours) is a measure of battery capacity, not current - the current you run through the cell will need to be measured with a multimeter or something (if you want to measure it, that is). Also note that if you've made your copper sulfate like this, your final acid product will likely still have a bunch of magnesium in there. Anyway, hope it works out for you!

[@ceasargaming9041]

@@ScrapScience ok yeah wow thanks man! would I just plug the phone charger into the outlet then? how do I know whats postivie and whats negative? also, wont it be AC instead of DC???? anyways, you should really make a discord man!!

[@ScrapScience]

USB chargers are DC on the output. If you plug it in, it converts AC from the mains into 5 volt DC to your phone. In this case, if you cut open a USB charging cord, you might be able to recognise the positive and negative terminals by their colour, or you might need a multimeter to check which pair is actually giving you 5 volts. And yes, a few have mentioned discord in the past, but I still feel like I don't understand it very well. I'll have to look into it a bit more, haha.

[@michaeltopping8227]

can you create a video of how to subtract sulphur from coal as i have been unable to find one also, can you make battery acid from sulphur using electrolysis

[@ScrapScience]

Sulfur from coal? Sorry, that's not really something this channel is going to delve into. Battery acid from sulfur by electrolysis is something that can be done using NurdRage's 'electrobromine process': kzbin.info/www/bejne/bJ7WZ6uYhc2XjNUsi=kojwVuhpyGSzWp0s I'll be trying this procedure in a future video at some point.

[@_retr0_210]

I tried using graphite, but it corroded all of it and made the solution blackish, after it I chose a Lead one, seems to work better

[@Berghiker]

Can you show how to make concentrated sulphuric acid using potassium nitrate and sulphur?

[@Preyhawk81]

Buy an big jar with lid of glas like the big Candy glasses . fill an little bit of water on the bottom put i iron ship on it put on the ship an mix of 12-15% Potassiumnitrate and 88-85% Sulfur. light it and close the lit. Repead until you reach an concentration of 70%.

[@somaghosh9557]

what is the current you used in this video

[@ScrapScience]

I believe I was using something in the range of 2 amps, which a lead dioxide anode can handle easily. However, if I were to use a carbon anode, the current would need to be limited to something like 0.1 amps so as to not damage the anode too quickly.

[@AlanCartman]

I've used over 2 amp. Time ∝ current. You have the equation Q=Ixt

[@kelvinpino4065]

It's easier just to multiply by the faraday's constant 96500, I mean 0.12 mols of e- are equal to 11580c

[@jakeeutis5035]

What was the ph of the sulfuric acid? I’m curious about the purity

[@ScrapScience]

I performed this experiment a long time ago, so I don't really remember, but it was definitely lower than 1. I've been able to produce concentrations above 2M with this method, and I believe it could be made much higher. As far as purity goes, it really depends on how pure the copper sulfate is. If the copper sulfate is recrystallised first, the final sulfuric acid can be made very pure.

[@sciencefusion5352]

1pound of hydrated copper sulphate can give you 100 ml of conc sulphuric acid this is my practical result

[@petrlaskevic1948]

@@ScrapScience How much current was there? I see from your diagrams that required voltage is very low, but I'd like to know how much current is needed. I have an old phone adapter I could use for this, using 400mA at 5 volts. Would that be enough?

[@masterminds1093]

Can i use a pencil graphite as the anode? Please answer as fast as possible scrap science

[@ScrapScience]

Yep, you’ll probably need a few though, because they don’t last too long

[@masterminds1093]

Another question. That is can i use a 9v battery?

[@masterminds1093]

@@ScrapScience Thank you so much dear...

[@ScrapScience]

A 9v definitely won’t last long enough to make any significant quantity of the acid. Your best bet is a big 6v lantern battery or a simple 5v DC wall adapter.

[@masterminds1093]

@@ScrapScience Thank you so much dear...😀😀May God bless you...

[@geniusdude8975]

Can i use lead rod instead of PbO2

[@ScrapScience]

You can, and that's what I've done in this video (as the surface oxidises to PbO2 anyway). However, I would seriously advise against using any kind of lead based electrode without the proper safety equipment and ability to deal with waste. It is incredibly easy to poison yourself if extensive safety measures are not taken. A much safer anode would be carbon or graphite, even pencil leads will work for small scales. If you can, please use that instead.

[@geniusdude8975]

Thank you

[@michaeltopping8227]

does this demo mean that, when i charge my car battery, i am in fact refurbishing the electrolyte(acid)

[@ScrapScience]

Correct! The lead sulfate on the electrodes in the discharged state will be converted into sulfuric acid as the battery is charged. The acid concentration in a charged lead-acid battery is significantly higher than in a discharged battery.

[@dragan3290]

Hi can I use plain lead bars?

[@ScrapScience]

Yes, but I'd seriously recommend graphite instead. Lead electrodes will inevitably introduce lead contamination to your solution, which shouldn't be handled without the appropriate setup. On reflection, the way I've done things in this video is not a safe way to do things, and graphite anodes are a much better option.

[@dragan3290]

@@ScrapScience thank you for your reply! I'm gonna try to search for rods ASAP . Cheers

[@nattsurfaren]

14:30 How to calculate this is concentration percentage? 200 ml,0.3 mol sulfuric acid.

[@Loskoragaming]

Can i use home AC current?

[@ScrapScience]

No. You need low voltage DC.

[@Taha-hv6yj]

Can I use gold instead? Lead is toxic :(

[@ScrapScience]

You can try, I've really got no idea how gold would hold up though. I'd definitely recommend using carbon rods instead, as they have no chance of forming anything toxic (even gold, if you manage to put it into solution somehow, would be incredibly toxic) and anything that erodes off the carbon can simply be filtered at the end.

[@mickgupta2139]

What was the voltage used

[@ScrapScience]

I don't really remember, probably something like 5 V. Either way, the voltage is not a critical element of this process, anything above 2 V DC will do the trick (though I'd keep to low voltages of around 5 V to keep the current and the reaction rate at controlled levels).

[@Berghiker]

Can you show how to make ANILINE DYE? (PURPLE MAUVE) color.

[@shibedoge7084]

Can zinc can be used as anode?

[@ScrapScience]

I'm afraid not. Zinc will easily dissolve into solution, and you won't end up generating any acid. The anode I recommend these days is graphite, or platinum if you can get hold of it.

[@amrendramishra545]

How make nitric acid

[@sciencefusion5352]

Will my lead dioxide anode Erode some day or it will give ma thousands of liters for sulphuric acid without getting destroyed ???

[@ScrapScience]

Lead dioxide will definitely erode over time, and has the problem of generating lead contamination. Eventually, you'll have to start filtering suspended lead dioxide from the product. Despite the fact that I use lead in this video, I'd definitely recommend graphite for small scale production, simply because it's so much safer and cheaper to work with. Graphite particles will need to be filtered out of the final solution of course. If you have plans for large-scale production, a platinum anode will be cheaper in the long run, and will (virtually) never need to be replaced.

[@sciencefusion5352]

@@ScrapScience can you tell me the life of lead dioxide anode ???? Because the advantage of lead is that it offers very large surface area which drives my reaction very fast . Can you tell me the lifr of the anode ???

[@ScrapScience]

The lifetime of an anode depends on lots of factors, including the temperature, the current density, the acid concentration you run your cell at, the purity of your copper sulfate, how thick your electrode is, and how you've made the electrode, just to name a few. My (VERY) rough estimates for electrode lifetimes are as follows (these all assume that you have perfectly pure copper sulfate starting material and a low current density): 1) If you have a professionally made titanium substrate lead dioxide anode, it will last a long time, and you'll likely be capable of making on the order of 10 L of concentrated acid total, before your electrode starts to fail. 2) If you have a homemade titanium substrate or graphite substrate lead dioxide anode, it will likely fail quite quickly, and you'll probably make on the order of 1-2 L of concentrated acid total (but it's likely to be a lot less than that), before your electrode falls apart. On top of this, running for a long time will fill your solution with a suspension of fine lead dioxide, which is tricky to deal with. 3) If you are just using a piece of lead metal as the anode, allowing the surface to oxidise and form lead dioxide, it will last a long time. It will fall apart relatively quickly, but since the entire thing is made of lead, it will continue working for a very long time (this time will depend on the thickness of the electrode). Of course, the lead contamination for your acid solution will be very high in this case, as will the amount of suspended lead dioxide in your solution. If you're really making large quantities of acid, you can search online for high surface area platinum on titanium anodes, which are MUCH better and more efficient for the process, and will last forever. electrodesupply.com/electrodes/ sells high quality, authentic platinum electrodes at reasonable prices (~$30), and you could easily put over 5 A of current through one of these electrodes (or 10 A through the bigger ones).

[@sciencefusion5352]

@@ScrapScience thanks thank you for this precious information 😊

[@michaeltopping8227]

just jokin, a great vid. i have a large solar battery bank, and i like to save money any way i can

[@vomitinside9104]

At 8:33 you wrote 0.12 as 012 by writing the 1 over the . What do you have to say for yourself?

[@ScrapScience]

I do apologise. You may also notice that at 5:09 I forget to write a minus sign after the 'e'. I hope this hasn't caused you too much trouble.

[@vomitinside9104]

Apology accepted, and good on you for admitting your other mistakes. I look forward to more Scrap-tastic science videos!

[@kelvinpino4065]

Why the lead dioxide didn't form lead sulphate just like in an car battery?

[@ScrapScience]

The oxidising potential is too high in this case. Oxidising the surface to lead sulfate is easy and only requires a very small voltage to push the reaction forward. To drive significant current though, our voltage is much higher than this, and allows for the oxidation all the way to the dioxide.

[@kelvinpino4065]

@@ScrapScience Thanks for answering! Aluminum sulphate is very cheap and available where I live, so is possible to use it to make sulphuric acid? Have you ever thought to use the plastic separator found in car bateries as porous membrane to electrolyze sulphate salts?

[@ScrapScience]

Yes, any soluble sulfate salt can be turned into sulfuric acid by electrolysis. Aluminium sulfate will require a separated cell, and the process is extremely inefficient, but it can be done. Ripping apart car batteries is definitely not something I'd like to do, even though the separators might be useful. The sheer messiness of the process, combined with the lead compounds makes me terrified honestly. I've also been unable to find anyone who will sell the membranes directly.

[@kelvinpino4065]

@@ScrapScience So despite the risk of lead compounds, is fair to say that PbO2 is as good as MMO or platinum coated titanium to use it as anode? I'm also interested in building a chlorate cell

[@ScrapScience]

Lead dioxide is only effectively inert enough to use as an anode if you’re electrolysing sulfate or carbonate solutions. And even then, I don’t recommend it. For anything else (e.g. solutions containing chloride, hydroxide, or for chlorate cells etc.), the lead dioxide electrode is not an option if you’ve made the electrode only by anodising the metal. The lead will quickly dissolve and fall apart, leaving you with a terrible toxic mess.

[@antunbartolovic3458]

Other way is adding hydrogen peroxide into solution of copper sulphate and then distill it (distillate will be H2SO4 and the rest will be CuO2). P.S. H2SO4 will not be concentrated.

[@firas4912]

this prcesse is expensive you must use calcium sulfate but in tube as form U or H , electrod fom Pb

[@Kristjan10a]

I found Sulfuric acid from my hardware store under drain cleaner. That was like a year or two agow. But now i dont finde it. Turns out that it was too dangerous to sell. Bummer.

[@peterbranton6845]

After reducing the solution down to less than 50ml from 330ml the ph is reading 0.3 but it for some reason will not react with sugar.

[@ScrapScience]

In regards to all of your comments/updates, nice work! I'm glad other people are trying the magnesium/ammonium sulfate method. As for your pH measurements, are you carefully calibrating your pH meter before every test? pH probes are notoriously inaccurate without extensive calibration every time you use them. Even with extremely expensive models, they will still be highly inaccurate at very low pH. Acid concentration is very difficult to infer from inaccurate pH values. To get even a reasonably accurate reading of concentration, you'll need to titrate it rather than just test the pH. As for why it's not reacting with sugar, you need VERY concentrated sulfuric acid to get that reaction to occur. Anything below around 80% won't work properly. It's very difficult to concentrate sulfuric acid to that degree without a powerful hotplate/heating mantle. An iron and a pyrex jug is clever, but unlikely to be able to reach the required temperatures of over 300C to get rid of all the water (and if it did, it would probably be quite a dangerous setup).

[@anjalibandi3427]

Where to get cuso4 where

[@sciencefusion5352]

Amazon

[@geniusdude8975]

Fertilizer shop

[@kenb8773]

Can anyone tell me what percentage 0.3M would be?

[@michaeltopping8227]

gan you subtract sulphur from coal and use that as coal is cheap

[@ScrapScience]

No. This process requires the use of copper sulfate, not sulfur by itself.

[@Berghiker]

So 200ml of 0,3M sulphuric acid should equal about 3.5ml conc H2SO4.

[@ScrapScience]

Yep, that's about right

[@Berghiker]

Why not test it with sugar?

[@ScrapScience]

The concentration here is nowhere near what is required to observe a reaction with sugar. That would require reducing the volume by boiling the solution (not something I have any desire to attempt at this stage).

[@Berghiker]

@@ScrapScience ok

[@EKSPLORASI]

Sir. Is the position of copper in electricity - negative. Please answer. Greetings success always.

[@michaeltopping8227]

do you do a "how to make a nuclear bomb" video

[@Jkauppa]

try welder as the current source

[@Jkauppa]

try getting metals from dirt using the sulfuric acid, regenerate the acid

[@Jkauppa]

battery acid at 35%-45% is easy

[@Jkauppa]

you could put a resistor like 20 ohms (or 220ohm) in series to limit the current from a battery source

[@Jkauppa]

a diode in series with a resistor is a nice voltage current regulator reaction setup

[@Jkauppa]

say 8 ohms resistor at 9V battery through 2.7V diode gives max 0.3375A and 0.9W of power through the setup cell

[@YouMockMe]

I get this crap from my still.....smh, I kept tossing it away. Subscribed!

[@1ZZFE]

The problem is... Where do I get copper sulphate in my country. 😂

[@OSes_algodoo]

Huh, only some EU country ban it, you can try to buy some when you travel

[@technofreax]

I think you should not use plastic bottle

[@bearcatben4762]

Polyethylene tetraphtalate is highly resistant to sulfuric acid

[@Relatablename]

@@bearcatben4762 It's really not at all. It'll hold up against low concentrations in the short term, but should not be considered for storage or going anywhere near sulfuric above 30%.

[@bearcatben4762]

@@Relatablename I am just saying what I know from a materials data sheet if you say so say it

[@DimebagGaurav]

Soldering gun on the pizza

[@putinscat1208]

I think you need some proper beakers.

[@malcolmcliff-du8qp]

So ive just wasted my time with clay pots LMAO

[@ganeshyadav-ey3je]

Can you show more ex

[@BritishBeachcomber]

Loads of videos like this, all made by amateurs who don't really understand chemistry. This is the first one that actually bothers to balance the equation.

[@wat8437]

The part with you making a cable is unnecessary. It doesn't really add to the video it take take up time where you could've provided more information about the process. Interesting video nontheless