Making Rust Quickly: 4 Methods I've Tried

[mrjeffy321]

Hello, I want to make some rust (iron oxide, Fe2O3), and I know there are many ways of going about this, but I would like to be able to get a significant quantity and be able to use it within a short period of time.

Here are the 4 methods I have tried:
-electrolysis, putting a piece of iron on the annode and letting it corrode, but this takes a long time to get it out of the water and it isn't very pure
-the old fashion was of putting an iron nail in salt water, but this takes a while to get any usefull amount
-next I tried putting some very thin steel wool into water (with and without salt), I am most pleased with this method because it seems to rust rather quickly and I don't need that much water to do it with, it won't take as long to evaporate off the water and get the rust, but it still takes too long to do that

-I know that if you "burn" steel wool, you are oxidizing the iron and making rust, well this is fast, and it should produce lots of rust, but when I trie it, it does produce a rather entertaining show with some sparks, but when it is over, all I have is a darker, more britter version of what I started with, I don't "see" any rust, but isn't that what it is suppose to produce?
if I could get this method to work, it would be my most preferable, it is the fastest and easiest in producing the most rust, but I can't seem to get the rust I am making, how can I do this? is it becase that even though the iron is reacting to make the rust, the other elements in the "Steel" wool are keeping it from being gotten some how?

any other fast mean of making the rust would work to, but I would still like to learn what the problem is with the steel wool method aswell.

thanks

 

[chroot]

The fastest and easiest method to make rust is to put some steel wool in a dish full of vinegar, then add a little bleach. It'll turn to rust nearly instantly. WARNING: THE PROBLEM WITH THIS METHOD IS THAT THE SOLUTION EVOLVES CHLORINE GAS, WHICH IS HIGHLY TOXIC, HARMFUL TO THE EYES AND RESPIRATORY TRACT, AND CAN KILL YOU. IF you attempt to use this method, do it outdoors, hold you breath when adding the reagents, and don't go anywhere near the dish for at least a few minutes after combining them. Please be extremely, extremely careful with this method.

- Warren

 

[mrjeffy321]

wow, you are so helpful.

I am well aware of the dangers of chlorine, and will be carefull while doing this.

 

[Gokul43201]

I think peroxide would work as well (if not better)...but it is easier to find bleach.

 

[mrjeffy321]

well, I am still trying to find out what the problem is with the burning of the steel wool.

I am also trying to know exactly what is going on with the bleach + vinegar reaction, what is the reaction formula for that?

bleach is NaClO right?
Fe(s) + C2H3O2(aq) + NaClO(aq) ---> F2O3(s) + Cl2(g) + ...

does it make sodium hydroxide, and then the hydroxide make the rust, is CO2 produced too?

 

[chroot]

Well, you probably don't have nearly a large enough temperature to actually burn iron with a standard lighter. All you're doing is depositing carbon soot on it.

Also, I mixed up my reagents -- you need a 2:1 ratio of bleach to vinegar, so you're better off immersing the steel wool in bleach and adding some vinegar, not the other way around.

I'm not quite sure about the full chemical equation for the reaction, but I'll work on it a bit and see if I can figure it out. Keep in mind as well that rust is typically anhydrous, Fe203 * 5H20 or something...

- Warren

 

[mrjeffy321]

well, I am not totaly certain, but I have seen my idea of the steel wool "rusting" confirmed from various other sources, also when I do burn it (by means of a 9 volt battery or flame, long after I take the heat source away, the reaction continues, it does look like something besides just soot is happening. It is like it is burning in slow motion, the steel wool nearest the heat turns red/orage and throws off sparks and smoke and this continues upward until all of the availible wool is used up and after it is done you can tell that something has happened and you cannot react that same piece again.

when this [the reaction] is over, I want to collect this rust, without if possible, also collecting the remnents of the reaction that I did to make it, will this be possible. for example, when I rust somehting with salt water, in order for me to collect the rust, I decant and then evaporate all the water I can, but this leaves the salt behind which mixes with the rust, what will be left behind from the bleach and vinegar reaction?

how does this reaction look, could this be close, it is unballenced of course

Fe(s) + C2H3O2(aq) + NaClO(aq) -> Fe(s) + Co2(g) + Cl2(g) + NaOH(aq)

the iron does nothing in the first reaction, but the acedic acid and bleach make chlorine gas and carbon dioxide, and they bubble away and are out of the reaction, that leaves the iron and the sodium hydroxide

Fe(s) + NaOH(aq) -> Fe(s) + Na+(aq) + OH-(aq) -> Fe2O3(s) + H2O + Na+

then the sodium hydroxide breaks up into ions and the hydroxide ion goes and splits up to make the Iron(III) oxide and more water, leaving just the sodium ion behind, but this last part seems wrong to me, possible there is stil some chloring hanging around from the first reaction to make sodium chloride, but that doesn't seem quiet right either

or even better yet, how about this one, but it doesn't produce chlorine gas:
2Fe(s)+ 2C2H3O2(aq) + 7NaClO(aq) -> Fe2O3(s) + 3H2(g) + 4CO2(g) + 7NaCl

 

[mrjeffy321]

you know what, none of those formulas that I gave above is correct, because I forgot the extra hydrogen on acitate to make it acetic acid, so all of those are wron, and if you just mentally add in an extra hydrogen, then I don't thnink it will work, the hydroxied would perhaps combine with it and make water, and then leave out the sodium again.

 

[Gokul43201]

Actually, I believe it's the following :

Bleaching action is simply oxidation by nascent (atomic) oxygen released from the bleach :
3NaOCl + 2Fe -> 3NaCl + Fe2O3

The other reaction that simultaneously occurs (even in the absence of iron - yes, this is what makes bleach smell of chlorine gas) is :

2NaOCl + 2H(+) (from vinegar) + 2e(-) -> 2NaOH + Cl2

 

[mrjeffy321]

ok, so basicaly the vinegar is just speeding up the reaction, it isn't necesary.

and the bleach only reaction, amkes the rust, along with plain old salt water, sow I just need a wa to separate the rust from the salt.

 

[zoobyshoe]

The heating of the steel wool is interesting. If I am understanding you correctly there is something left over when the burning stops. Everything doesn't convert to smoke.

If what is left is black, and very brittle so that you can crumble it easily, it is probably Fe₃O₄. This is magnetic oxide of iron or Magnetite. If you can attract it with a magnet, I'll bet that's what you've made. If you can't, then it is something else.

I wonder about the smoke. It could be that the manufacturers coat the steel wool with some very light oil so stave off rusting. Just a guess. This might account for why it burns by itself.

There is another possibility, which is that in the heating, somehow, ferrous oxide (FeO) is first formed. FeO has the property that it burns spontaneously upon contact with oxygen in the air. This might account for why it continues to burn by itself. Again just a guess.

If you put something like a dinnerplate in the freezer until it is cold you may be able to get the smoke from this burning to condense on it. If it is soot, you may be able to measure its resistence with a meter. That would indicate an oil coating on the steel wool. If it won't conduct, it may be one of the iron oxides.

I made a whole bunch of rust a couple years ago with old nails and vinegar water. I can't for the life of me remember what I wanted it for. Anyway, I put the nails and vinegar water in one of those cheap little rock tumblers so that the rust would continually be scraped off the nails as it formed. Once in a while I poured the liquid out through a coffee filter, added more to the tumbler and set it going again. You can wash the rust as many times as you think you need to and get rid of most of the water with the coffee filter method, which is cheap. Each time you do it you lose some of the rust to the filter, though, can't scrap it all out.

-Zooby

 

[Gokul43201]

Salt is soluble in water; rust isn't.

 

[mrjeffy321]

the material that is left over after burning the steel wool appears[to a color blind person] to be more blueish and darker than the original steel wool, it feels more brittle and flakes more easily. I think the resulting material is magnetic, but the magnet could just be attracting to the unreacted particles of the original steel wool that excaped burning, which was magnetic to start with. when I soak the resulting steel wool in water, it appears to do the same thing as the normal steel wool, nothing at first, but slowly the water turns brown as it gets filled with rust.

I have seen places online that claim that burning the steel wool does infact make Fe2O3, but I cannot find any right now. perhaps it does, but the extra heat of the reaction makes a second reaction to turn the Fe2O3 into the magnetic Fe3O4.

 

[Gokul43201]

That probably is Fe3O4 (my guess) you are seeing. It is often referred to as mill-scale in the heat treatment of wrought steels and is generally described as black in color. You may have seen blue from the HAZ (heat affected zone -like near a weld joint).

The oxidation state of Fe in Fe3O4 is +2.67. When this is dropped into the bleach solution, it gets further oxidized to the +3 state (in Fe2O3). Also, this will make much less salt (NaCl) than if you just used the plain steel wool.

Another thing you could do, if you had a sensitive balance, is weigh the steel wool before and after burning. If you measure more than a 65% increase in weight, you definitely have Fe2O3 in there.

 

[BobG]

I can vouch for MrJeffy's claim that steel wool does indeed burn.

Wrapping some steel wool around one end of a pencil, igniting it, and setting the other end in a centrifuge gets quite a reaction from the other students (not that I've ever tried this ... at least not more than once).

From a functional stand point, steel wool is a great compliment to a steel/flint firestarter kit. It can take hours to actually get wood shavings to ignite from the sparks given off by flint and steel unless you're really good at it. Mashing your wood shavings into a pad of steel wool and then refluffing it allows you to get your fire started a lot quicker. The steel wool ignites just about the first time any spark hits it. It burns quickly, so you want the wood shavings intermeshed in the steel wool. They burn a little longer and give you enough time to start adding more wood.

If you sort your laundry and wash cotton separately, the lint from the lint screen in the dryer works nearly as well as steel wool (maybe that's why the dryer manual says to clean the lint screen before every load).

 

[mrjeffy321]

will non magnetic Fe2O3 naturaly turn into Fe3O4 on its own, just by using the energy from its surroundings?
because when making the rust, it starts out redish brown and appears to be non magnetic, but now the older stuff that has been floating around in the water the logest has turned much darker, and the stuff that I have dried out, a lot of it is attracted by a magnet. so that is why I am thinking I am getting a lot of this magnetic dark stuff, the Fe2O3 is slowly changing to Fe3O4 on its own, I though you had to apply a lot more heat to get it to change.

 

[chroot]

Have you tried bleach + vinegar yet?

- Warren

 

[mrjeffy321]

yes, I basicaly have 2 batches of rust right now; the stuff I made early on with salt water which I have dried out about half of it, and I also have the bleach and vinegar batch which is still very wet, that will probably take another day or two to dry depending on the weather. but even the stuff I just made today with bleach and vinegar shows signs of turning dark and there is a "skin" developing on the water, and some of it is magnetic.

 

[chroot]

You seem to be very concerned about the purity of your rust -- may we ask what the rust is for, and why its purity is so essential?

- Warren

 

[mrjeffy321]

yes, I guess it might seem like I am very concerned about the rust purity, I think that is just is the way I am, I like to have things pure unless I intend to mix them, but I don't think I absolutely need pure Fe2O3 rust.

I was intending to make the rust for a little thirmite reaction I wanted to try by burning Aluminum powder with the rust to make pure Iron and Aluminum Oxide, plus a lot of excess energy
but I don't think the purity of the rust will be all that important to this reaction

 

[zoobyshoe]

And what's the thermit for?

 

[mrjeffy321]

it is not for anything inparticular, yet, now it is just to prove to myself I can do it and get a feel for what it is like in person.

I am fully aware of the intense heat generated by this reaction, and the potential dangers associated with it, but there are legitimate reasons for thermit, for example it is a crude way of welding if you don't have another means, or any other activity that requires lots of heat.

 

[chroot]

Thermite's pretty fun -- and really easy to make.

- Warren

 

[zoobyshoe]

There are vastly safer ways to weld in all circumstances nowadays. Thermit was used way, way back, mostly on railroad repairs in remote areas. Sometimes on big machines, like when some 13 ton thingy cracked and couldn't have been heated with conventional torches. No one welds with thermit anymore.

Easy way to melt steel: hold a rod, say 1/4 diameter with a thick glove, and heat the other end to red heat with a plumbers propane torch. Then touch a piece of solid sulfer to the rod. The red hot metal will become liquid and drop off.

 

[Gokul43201]

There are vastly safer ways to weld in all circumstances nowadays. Thermit was used way, way back, mostly on railroad repairs in remote areas. Sometimes on big machines, like when some 13 ton thingy cracked and couldn't have been heated with conventional torches. No one welds with thermit anymore.

On the other hand, they still make incendiary bombs out of termite...

EDIT : I'm sure I meant 'thermite'. I really don't know of any bombs made out of termites, though that may not be such a bad idea really !

 

[Sarevok]

You can simply mix a saturated solution of an hydroxide (such as sodium hydroxide, "lye") or of ammonia to a saturated solution of an iron salt (such as iron sulfate, chloride, nitrate, anything - as long as its soluble, that's it). Ferric hydroxide will precipitate. You then filter it and leave it to dry; ferric hydroxide is unstable and turns to ferric oxide (rust) as it dries.

More information on thermite can be found at The Forum (www.roguesci.org).

 

[mrjeffy321]

first I would have to make the iron salt, sice I don't just have it laying around the house. I could do this by adding the iron to hydrochloric acide, and make iron cloride, then add the potassium hydroxide to it, this might work well, i'll try it if I ever get a chance, but for now i'll stick with the bleach method it is working good.

 

[Roarixer]

Just curious but what will your environment be when you perform the thermite reaction?

 

[stamba]

I think that you have to do is this:
FeCl3 + 3NaOH -> Fe(OH)3 + 3NaCl
Then just heat it up
t
Fe(OH)3 -----> Fe2O3 + H2O

 

[mrjeffy321]

I think that you have to do is this:
FeCl3 + 3NaOH -> Fe(OH)3 + 3NaCl
Then just heat it up
t
Fe(OH)3 -----> Fe2O3 + H2O

yes but first, I have to make the FeCl3, or any other iron salt.



in reguards to my thermite reaction, I haven't done it yet, I had hoped to do it today (the 4th) but last night I was trying to do a small test and I couldn't get it to light. I know you need massive amounts of heat the start the reaction, close to 1800, 1900 degrees F I think, but I didnt have any magnesium, sparklers, ... that could get that hot, so I tried a long shot with some model rocket engine powder crushed up, but it didnt work. I do have a blow torch that, in theory, can get that hot, but that would mean I have to be considerable closer to the reaction when it starts and that isn't entirely safe.
if you do have any suggestions on how I could light it other than the ones I described above, please tell me.

 

[chroot]

Go to Wal-Mart, or any camping store, and buy a magnesium fire starter. It's basically a block of solid magnesium and a scraper. You can scrape off plenty of little magnesium filings, ball them up, and light them with just about any flame. They'll burn hot enough to ignite your thermite.

- Warren

 

[mrjeffy321]

this thread just gets more and more off topic doesn't it, but that's OK I suppose.



I didnt know those were magnesium, I thought those fire starters were flint, i'll try that.

 

[mrjeffy321]

apparently those things are magnesium.

so i got one of those fire starters, and I carefully scraped off some of the magnesium into a pile (it took a while because sometimes I would accidently ignite the pile and I would have to start over). then i put it with my mix of thermite and lit it, it burned very fast with lots of intensity, but I don't think it ignited the thermite.
the thermite powder was slightly damp, and didnt change much after the Mg powder burned, so I don't think anything happened. I guess I didnt have enough powder for it to get hot enough. anyone know off the top of your head how how I need to get it, I though it was around 1800, 1900 degrees F, and it is advertized that the Magnesium stuff can get up to around 5000 degrees.

I'll try more later

 

[Brennen]

i have an idea. find somebody you don't like, and attempt to ignite the thermite on the hood of their car.

just a thought.

 

[mrjeffy321]

yes, that seems to be a popular activity done with thermite, but it takes me a considerable amount of work just to get 1 ounce, so I don't think i will be wasting it like that.

still haven't tried a larger amount of magnesium yet, I was on a vacation (to rocket camp by the way) so my next trip to wal mart, i will try to pick some up.