Make Iron Oxide (for Thermite)

Make Iron Oxide (for Thermite)

Warning: The electrolysis method in this video produces hydrogen gas, perform either outside, in well-ventilated area, or in an electrolysis box. Ferric chloride is corrosive, wear gloves when handling it. Greetings fellow nerds. I’ve gotten a lot of requests for this so in this video we’re going to make iron oxide for use in the famous thermite reaction. And we’re going to show three ways of doing it. However first I need to crush your expectations: Iron oxide is generally cheaper to buy than it is to make. It’s only cheaper to make if you have free scrap iron. As usual our objective here is to explore the science. Now our first, and worst, approach is straightforward rusting. Iron when exposed to water and air, will spontaneously rust. Here I’m using a pad of steel wool that i’ve soaked in salt water. The water helps to accelerate the reaction with air. As I leave it out you can see it rust over the course of a few hours. While this method does work the rust layer is rather thin and you need to keep it wet to keep the rusting going. After a few days the steel wool pad will crumble into a powder of iron oxide rust. Any unreacted wool will need to be soaked again and allowed to continue rusting. The resulting powdered rust is actually a mixture of iron oxides, iron hydroxides, and unreacted iron. You can convert the iron hydroxides to iron oxides by heating the powder to drive off the water. This iron oxide is somewhat low quality due to the presence of unreacted iron. You can improve the quality by separating out the unreacted iron with a magnet and re-soaking it. You can also burn the steel wool before you start. Now making iron oxide by rusting is just barely viable for extremely fine iron like steel wool. But for bulk iron, like nails, this is just far too slow and labor intensive. For this you’ll need to use either the wet chemical process or the electrolytic process. In the wet chemical process we first convert our iron metal into iron chlorides by dissolving them in hydrochloric acid. I already have a video on this process which i’ll link the in video description so i won’t waste your time here. You can also skip the oxidation parts of that video using hydrogen peroxide or air as the thermite will still work. Anyway, get your solution of iron chlorides and start adding sodium bicarbonate, also known as baking soda. I’m using an iron chloride solution that’s actually a waste product contaminated with other metals from one of my other experiments. So if yours is a different color don’t worry about it. Anyway what we’re doing here is converting the iron chlorides into a mixture of iron hydroxides and iron carbonates which will precipitate out. Keep adding the sodium bicarbonate until the solution stops bubbling. Now you might run into the situation where the precipitate becomes so dense that it turns the mixture into a thick paste. If this happens, you’ll need to transfer it to a larger container and add enough water to make it fluid again. Now before anyone makes that joke in the comments, yes i am aware this looks like i’m stirring around a piece of turd. Anyway, continue adding the sodium bicarbonate. Looking back i probably should have started with the bigger container but oh well. Once again keep adding sodium bicarbonate until it stops bubbling. When that point is reached we have a mixture of iron hydroxides, carbonates and salt. Now we need to separate the two but we can’t use filtration because the particles are so fine that they’ll clog up the filter paper and stop the filtration. So instead we’re going to use dilution and decantation. To do this, add water and massively dilute the mixture. Fill up your container almost to the top. It’s important to use a lot of water. You’ll need at least ten times the volume of the precipitate for this to be effective. Stir everything and then let it settle for half an hour. The insoluble iron hydroxides and carbonates will quickly settle to the bottom, leaving behind the solution of salt and a very small amount of suspended iron. This ability of iron to bind together suspended particles is also used in some types of water treatment systems to remove things like dirt, wastes, or even harmful pathogens. Moving on, once the mixture is sufficiently settled. Decant the supernatant by siphoning it off with a tube. I don’t recommend tipping the container and pouring it as you might kick up the mixture and lose some of your product. Once you have most of the supernatant out you can stop here but i’m going to wash out more of the salt by adding fresh water back in, stirring, and repeating the process. This is to ensure i remove as much of the salt and unreacted sodium bicarbonate as possible. I did this two more times for a total of three. It was very hard to remove the last bit of supernatant without also siphoning out the precipitate so i didn’t bother. Now the remaining precipitate is allowed to dry. As it dries it will actually break up as it loses water and contracts. Heat the resulting pieces to drive off the remaining water as well as convert the iron hydroxides and carbonates into iron oxides. This method is fairly robust for moderate amounts of iron oxide and is easily scaled up. But if you don’t like spending money on hydrochloric acid and sodium bicarbonate then you can try making iron oxide by electrolysis. The best way i found was to start with a nearly saturated salt solution. I’m using 400 mL of water and 120 grams of table salt. The higher the salt concentration the more conductive the solution is and allows you to use more current, making the electrolysis proceed faster. My solution is a bit dirty from using a dirty stir bar, but it will still work. Anyway, stop stirring. And for our anode stick in an iron object like a nail attached to the positive side of a power supply. This will be the source of iron for the iron oxide produced. Now for our cathode, we get a wire attached to the negative terminal of our power supply. I’m using iron wire but you can also use copper. Now turn on the power. Adjust the current so that just the cathode bubbles. You want the iron anode to dissolve but not to bubble. If you don’t have a variable power supply like i do, you can also raise the wire so less of it is in solution and reduce the current that way. What’s happening is that at the cathode, or negative terminal, we’re reducing water with electricity to form hydrogen gas and hydroxide ions. Now hydrogen gas is flammable so you should do this either in a fume hood, outside, in a well ventilated area or in the handy electrolysis box i showed in an earlier video. Anyway, at the anode, or positive terminal, we’re oxidizing iron to form iron ions that react with the hydroxide ions to form iron hydroxides. The reaction is actually a lot more complex than this with numerous side reactions like the formation of iron chlorides, sodium hypochlorite bleach, iron oxychlorides, oxyhydroxides and other chemicals. But overall this is what’s happening. I said before that you didn’t want too much current to produce bubbles at the anode because when you overvoltage the system the anode will start oxidizing water to produce oxygen gas and some chlorine gas. Both of these waste power and don’t contribute to the formation of iron hydroxides. Now you might be wondering if there is any special reason why i used table salt as the electrolyte. Actually there is. I first tried sodium bicarbonate baking soda and while it did work at first the iron quickly passivated and stopped further current flow. The electrolysis stopped despite there still being plenty of electrolyte and electrodes available. I then tried sodium bisulfate which is an acid available as a pool chemical. This worked but the instead of precipitating out, the iron in solution just migrated over to the cathode and started plating out. It’s a fun way to make iron filings but a useless way to make iron oxide. Only salt worked effectively and was commonly available enough for everyone to try. Anyway, let this run and after a few hours you’ll notice the iron anode dissolving or developing a crust as seen here. Don’t worry the crust is just some adherent iron hydroxide and easily comes off. As you can see, the actual iron nail has been greatly corroded. We’ll put this back in for further electrolysis. If it corrodes away completely then you can switch it out with another source of iron, Now I recommend rotating your electrodes to get maximum use out of them. As the iron hydroxide forms it will fall to bottom of the cell so it’s important you have a container big enough to contain it. You don’t want the electrodes getting covered in the rising level of iron hydroxides as that will insulate the anode from the reaction. And if it gets on the cathode it will start plating out of solution as iron metal which you don’t want. Oh yeah, one more thing, remember to top off the cell with water as it evaporates. Anyway, after a few hours or days, when you’ve either run out of iron to convert, or have filled up the cell with too much iron hydroxides, remove the electrodes and filter the solution. Be sure to wash the residue with water to remove any salt. Alternatively instead of filtering you can also use the same dilution and decantation method i showed for wet chemical iron oxide. Now let it dry. Break up the chunks and dry it to remove any remaining water as well as convert the iron hydroxides to iron oxides. An interesting thing i noticed as i was heating this is that it slowly went from black to red with repeated heating and cooling cycles. Red is the common color of high quality of iron (III) oxide. It was quite amazing to me see black crud become red crud. Yes i am still easily impressed despite having a Ph.D. Anyway, that is how you produce iron oxides. Personally i think the electrolytic method is best as it strikes a good balance between speed, cost and quality. Now to use them in thermite just mix the iron oxide with one third its mass of aluminum metal, and ignite it with a sparkler or magnesium ribbon. I’ll be exploring thermite in a later video. Thanks for watching.

100 thoughts on “Make Iron Oxide (for Thermite)

  1. steel whool aint what it used to be , they changed the alloy and now it doesnt burn well at all and it doesnt rust as bad

  2. mayb u can cleensweep a mechanic-shop (iron oxide from welding and grinding)
    -or even a dockyard.
    I came across a bulkhead wall lately where large chunks of rust fell off.

  3. You can also perform the electrolysis inside, near candles. This drastically increases the chance for hydrogen combustion setting the entire room and you on fire.

    I don't know WHY you would want to set your face on fire, but you can.

  4. OH Nurdrage you should know better than to bleat on about the dangers of Hydrogen gas from a piddly little apparatus like this, I mean COME ON GRASS HOPPER !..REALLY ?! I would have expected you to know that the amount and dilution and the way that hydrogen just loves to go zipping upwards and in the process dilute itself to oblivion results in approximately a snow balls chance in hell of ever causing a danger, hell, you'd need a thousand or more of those things set up in a closet to get a bang…why do you lot always go spastic on the safety aspect instead of telling people the truth ? you and I both know just how NOT deadly most things really are, kids go look at an old 1900's chemistry book and see how those guys TASTED elements and compounds to characterize them…and for the most part that is perfectly ok, sure, there are exceptions, but even things like cyanide can be perceived without KILLING yourself, why not teach them the truth ? rather than this rabid over the top bullshit about how everything is deadly poisonous, I am a lab tech and this sort of thing really irritates me.

  5. So I used baling wire and ended up with some blue fluffy particulate and some tan color fluffy particulate. they both settled to the bottom of separate containers after I decanted the electrolysis flask. Any idea? I should note that the Erlenmeyer was cleaned with borax hand soap, I'm thinking that some glycerin or something of the sort is the culprit.

  6. +Nurdrage Is there any difference between using steel, like a nail, and iron, like pieces from a broken up cast iron sink? I'm assuming no (of course we all know the perils of assuming ?). Do you think either would be more likely to be alloyed with other metals, and would those metals interfere with anything? I'm also thinking in terms of other uses, including making ferric chloride.

  7. i did electrolytic and ended up with a really fine dry black powder, so i have iron hydroxide?

  8. why don't the ions from the sodium chloride electrolyte react with the iron or hydroxide ions? why do they only react to form iron hydroxide instead of iron chloride or sodium hydroxide?
    EDIT: Ah, don't worry he said in the video, but won't the final product be contaminated with these compounds?

  9. does electrolysis works with metal from foods can boxes? and oxydation ?And  what is the product when we don't use salt?

  10. I have had a problem when dissolving black sands in aqua regia that I end up with much to much dissolved iron which you have identified here as iron chlorides. I will test it when I get the chance, but would using sodium bicarbonate and I precipitate iron hydroxides and iron carbonates, will it leave the aurochloric acid behind to later precipitate out with SMB? If I use the dilution and decanting method to filter it does the dilution adversely affect the aurochloric acid or can it simply be evaporated to a more concentrated state.?

  11. Sorry, I'm not an expert chemist, but what if I repeat the electrolytic process using NaOH as electrolyte? I wouldn't have so much side reaction and my product would be "better". Don't you think so? Am I wrong with something?

  12. My problem with thermite is whenever I try to light it, the little buggers crawl off into their hill.

  13. Great vid very informative, been using FE304 for a biochar fertilizer mix, it was expensive to buy here in Northern Thailand so I was looking at making it myself, you have put me off the idea, mission accomplished

  14. I think the most efficent way of seperating water from iron hydroxide is boiling off the water, also you can keep boiling after the water is gone to convert the iron hydroxides to iron oxide, i used this method for my experiment

  15. Have you noticed any differences in speed to produce or quality of; between type and quality of the raw/scrap iron? Example: Does the different reactions take longer or provide more pure results between something like a treated nail, (such as you were using) and an untreated iron like cast iron?

  16. mine did the same as the electrode one and i had a blueish green soulution and when exposed with air turned red powder so thats weird…

  17. Im making iron oxide from vinegar, Should I chemically clean it for a better burn? Also, What burns hotter, Iron oxide or copper? Would you do a video on the two different thermites? I find that just learning the different methods of making Iron oxide is very amazing.A very big fan.

  18. Found a nice way to remove the salt. Boil down the iron oxide tell dry in a pie tin and use a large magnet on the bottom. The iron oxide is easily rinsed with no loss.

  19. I understand the goal was to make iron(III) oxide. But, I was wondering if the electrolysis method, when dried heated in an anaerobic environment, produces iron(II) oxide, or magnetite, or something else. My last question is, what temperature is needed to convert the iron hydroxides to iron oxides. My goal is to make a magnetic powder to mix into a epoxy forming a composite material with magnetic properties, that can be easily formed.

  20. A variable power supply was recommended, but I have old computer power supplies that can supply 3v, 5v, or 12v.

    I suspect that 12v will certainly go faster, but risks over-volting. Most PSUs can supply the most watts on the 5v rail, and 3v would end up being the most efficent, but will take longer and or require higher surface area for the anode and cathode.

  21. If you want to donate me a laboratory glass ware just add me my account is james capua in fb only then add me.. donate only glass wares thank you..

  22. Also u can use NH4NO3 for electrolyze, if you don't need this shitty Na-ions in thermite

  23. Just a question, in the case of iron ore (like hematite), do you need to proses it or is the iron already some form of iron oxide?

  24. I heard that if u heat up and evaporate all the water in ferric chloride it will decompose and make red iron oxide and chlorine gas. Could u do an episode on it?

  25. Do I understand this in the right manner? I can make iron oxide by burning the steel wool? Is the resulting product the same iron oxide as the product with the salt water? It is a dark blue product! Or does the ignited steel wool rust with salt water?

  26. Very fine steel wool is easy to ignite and burn. Any pros or cons for burning steel wool compared to the methods in the video?

  27. 3:50 That looks just like a Martian atmosphere. Interesting thing is that the real Martian Atmosphere does consist of some suspended iron oxide, which is what you're seeing in the video.

  28. “Yeah I’m still easily impressed despite having a PhD” ? this is my favorite science channel and I thank you greatly.

  29. Nerds making fun of nerds are turds. Also my uncoated neodymium magnet says ouch at 5:50 btw yes jeffinetly like the way you explain it it makes sense to me

  30. Why You Didn't Try Sodium Hydroxide? It Will Oxidized The Iron To It Oxide & NaOH Regenerate, It Produced Hydrogen At The Copper Cathode, So it doesn't corroded.

  31. How about this:

    1, Steel wool into the grill separated from the fire so it only get really heated up.
    2, Water+NaCl+the steel wool–>Fe2O3
    3, Heat the powder upp to make the iron hydroxide get into iron.
    4, Use magnet to separate Fe2O3.
    5, You now have got pure Fe2O3.

    This should be an easy way to get many kilograms of Fe2O3.

  32. what about boiling down urine and using for electrolyte? the urea with the salt somehow cooperate that it can get very concentrated so you get even more current.

  33. dont use such low surface area electrodes. go buy two short pieces of construction steel like L or U channels or flat steel. then you can run more current without overvolting the electrolysis.

  34. تحياتي اجانب ممكن تكتبوا كيف يتركب هيدروكسيد الامونية مع كلور الماء

  35. I work at an auto parts store, where we have a brake rotor lathe. I got just about all the iron filings I want!

    If your nearby store has a brake lathe, you might could ask for them to give you some. It just gets dumped in the dumpster anyway.

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