Make SULFURIC acid from WEAK oxalic acid with the SUN

In this video we're going to make sulfuric acid by the oxalate precipitation method.

The idea is rather simple, oxalic acid produces insoluble metal oxalates with a lot of metal salts. But in doing so, the salt anions are left behind in solution and become their respective acids. So a metal sulfate can be converted into sulfuric acid by removing the metal ions with oxalic acid. The conversion isn't perfect, but it's good enough to give better than 50% yield under the right circumstances.

300g of Iron (II) sulfate heptahydrate was mixed with 1L of water and stirred until dissolved. Then 200g of oxalic acid with heated with 300mL of water until dissolved. The two liquids are mixed and iron oxalate precipitates out. This can be filtered but for improved yield, i found leaving it out in the sun to photolyze any dissolved Iron (III) oxalate for 8 hours increased yields by 10%. After filtration the filtrate is boiled down until it starts to crystalize and then cooled and filtered again before the filtrate is distilled at high temperature to get sulfuric acid. Effective yield was around 67%.

I wasn't able to get Magnesium sulfate or copper sulfate to work. I think magnesium sulfate just doesn't work, but copper sulfate produces ultrafine copper oxalate that can't be filtered.

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[anon-means-anon]

It's crazy to think how much my life has changed since first finding this channel. I have got married, had a kid, bought a house, paid it off, and had my 12th anniversary in the meantime. The videos have stayed at the same high quality. No annoying sponsorships, no over the top clickbait, just good repeatable information. Here's to another 15 years or so, Mr. Rage.

[mikemike-qxue]

I don't care what your mother says about you, you sir are a genius, and do not let anyone tell you otherwise.

[DangerousLab]

I thank you on behalf of the European amateur chemist (or wherever sulfuric acid is not available) for providing another alternative method to make sulfuric acid!

[monsterslayer]

feels kind of similar to how mathematicians insist on finding new ways of computing pi every now and then :D

[steamerpowered]

Awesome! Thanks for showing the stuff that doesn't work as well. Negative results are still results 😉

[richardunruh]

@NurdRage For really hard to filter stuff, I vacuum filter through a 10cm buchner funnel and filter paper with diatomacious earth. I really helps to add a round piece of course fiberglass cloth under the filter paper (slightly smaller than the filter paper): it adds lots of flow channels and also supports the filter paper so it won't blow through the holes in the funnel. You can also use plastic screen if it's resistant to whatever you're filtering. Just pre-wet the filter paper using water+DME and keep running the DME water until it runs clear. Rinse the flask and you're ready to go. Sorry for the late edit. One more thing that can really help: Seal the top of the funnel with a flexible film, like Saran wrap or even film from a condom (unlubricated 😉). It will compress the stuff above the filter and improve throughput. Caution: 14.7 PSI on a 10cm filter is (if I did the math right) almost 180 pounds of force! Wear safety glasses! And as I also found out, erlenmeyer flasks with a side arm are not always vacuum rated! Fume hood window & safety glasses saved me from my own ignorance/stupidity.

[jbone]

Oxalic acid is a cheat code for mineral acids

[spiderdude]

Yeah, I actually thought about this method being possible a few years ago. It seems like it violates the “can’t make strong acid from weak acid” principle, but it actually doesn’t. It’s because that’s not the only force at play here it isn’t as simple as the oxalic acid protonating a sulfate ion and generating sulfuric acid. That kind of reaction is still unfavored. But you’re dealing with the power of Le Chatelier‘s principle. Oxalate is an unusual anion, due to how insoluble some of its salts are. And those salts are still mostly insoluble even in acidic conditions, which is rare. So the reaction is pushed forward by the mass action and formation of insoluble iron oxalate, NOT the protonation of sulfate. That still happens, but it needs the much stronger driving force of removing oxalate from the equation to overcome the unfavorable energy barrier.

[RiehlScience]

To reduce the iron(III), just drop a piece of steel wool into the iron sulfate solution.

[TheOneAndOnlyMilk]

I was also playing around with the idea and found a way of making sulfuric acid from oxalic acid by heating oxalic acid together with regular magnesium sulfate epsom salt. when melted together it turned into a white sludgey liquid, which contained the sulfuric acid, which then could just be distilled off. Its also a really efficient method when making nitric acid, as potassium nitrate could just be mixed in with the dry oxalic acid and magnesium sulfate powder mixture. When heated the potassium nitrate reacted with the sulfuric acid and produced the nitric acid, which also could be distilled with ease.

[horatiumoldovan]

I bet you are unaware of the impressive number of people that became chemists fom your inspiration just by simply helping me pave my way to it since I made sure to perpetrate the passion for it and I'm pretty confident I'm not the only one.

[iBlueriginal]

6:00 As a reducing agent you can use regular iron wool. It reduces Fe3+ to Fe2+ while going in solution as Fe2+, gives a purer product and can be easily filtered off.

[fmdj]

I am unsure about the practical usefulness of this process, but it is very elegant and smart, nice job. Your videos have taught me a lot and this one doesn't disappoint either.

[zedigamer]

I think the reason why the copper sulfate method didnt work for you was that you did it all together. You need to add the two ingredients seperately in different glasses of (preferably hot) water, then wait till both solutions cool down (put them in the fridge), then mix them together. This way the copper oxalate is less soluble and sinks to the bottom. It worked fine for me

[BattleChemist]

I wonder if chilling the copper sulfate solution prior to oxalate addition would slow crystal growth and thus create "bulkier" particulates that would be able to be filtered on at least a frit if not even a paper filter.

[HerDerderp-nhvb]

Following this channel since 1999. Great stuff as always.

[kyleeames]

6:07 I totally thought this fine NurdRage video had been interrupted at the BEST PART by one of those stupid game ads. 😂

[snoowbrigade]

The least available part of this video was the sunlight lol.

[Spencergolde]

From a molecular bio approach, I think centrifugation is probably the best way to seperate the milk of coppernisia you made, though this requires a centrifuge. If you have one already this might be worth exploring

[Petemate]

Potentially the pore size of the is larger than that used by other amatuers.

It's always interesting to hear more examples of things that go against what you're taught in highschool/undergraduate chemistry classes!