Best Way To Produce Large Amounts of Iron(III) Oxide (Rust)

  • #1

Main Question or Discussion Point

I want to produce a large amount of rust for a thermite reaction, at least a 12 oz can full, in a relatively short period of time. By short period of time I mean maybe a week. Here is a post from another forum:

"What you're all missing is this: rust is oxidation -- it's a galvanic process. It needs oxygen from the air, and water to conduct electricity. Immersing the steel wool in water only slighly increases the rate at which it will rust. It will still take forever and a day.

If you put the steel wool in a solution of bleach and vinegar, however, it will rust in seconds. Why? Because bleach is a potent oxidizer, and readily accepts electrons from the iron. By itself, this reaction would also quickly reach equilibrium by itself, and not make much rust.

If you add vinegar (ethanoic acid), however, the acid rapidly snaps up the highly basic product of the oxidation reaction, and neutralizes it. The result is a reaction that can proceed quickly, and does not reach equilibrium until all of the bleach and all of the vinegar is consumed."

It appears that he contradicted himself in paragraph 2/3. He says bleach, vinegar, and steel wool will not produce much rust because it will reach equilibrium. Then, he says adding vinegar will produce rust rapidly and the result does not reach equilibrium until all of the bleach and all of the vinegar is consumed. Does he mean adding MORE vinegar to the bleach/vinegar mixture will produce more rust, or does he mean vinegar alone will produce more rust or....? I tried bleach/vinegar with steel wool and it didn't work very well. However, this was steel wool that most likely had a protective coating. I am willing to get some pure steel wool (my chemistry teacher has plenty) and try this again if this method will work. But first, which method would work better...just the vinegar, or the vinegar and bleach. Oh, and by the way, I AM aware that bleach/vinegar produces chlorine gas or chlorine-like gases that are dangerous. I will be doing this outside and I didn't die last time, so I think I'll be fine.

EDIT: Should I take a piece of iron to a grinder and just use iron filings instead of steel wool? I believe using steel wool would result in more impurities in the rust, would it not?

-James
 
Last edited:

Answers and Replies

  • #2
mrjeffy321
Science Advisor
875
1
Do not over complicate it. Using bleach and steel wool is a quick, easy, and relatively safe way to make iron oxide (“rust”).

Make sure you use the right type of bleach. You want to use chlorine bleach (bleach that contains sodium hypochlorite, NaOCl), “Clorox Bleach”.

Make sure you use the right type of steel wool. You want just the very basic steel wool, nothing fancy that has special rust-inhibitors or soaps that you might find in the dish cleaning section of the store. Instead look for it in the paint section of a hardware store (the rough steel wool pads can be used used similar to sand paper). A good brand that I recommend has packaging that looks like this,
http://www.steelwool.biz/images/SW 8pad--pack-a_thumb.gif

Letting the steel wool pads soak in the bleach will cause them to rust. You will start to see the effect very quickly (in a matter of minutes). Over the course of hours to days the steel wool pads will thoroughly rust, producing a reddish-brown powder that will settle to the bottom of the container. Depending on just how much steel wool or bleach you use, you will likely have too much of one or the other. If you have too much steel wool then all the bleach will be used up and eventually the rusing will slow down dramatically. If you have too much bleach then all the steel wool will be used up and it will all oxidize away into the rust powder. It does not matter if you do not get the balance right, the rust produced will be the same.
 

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