[Bionic Person]

So, I attached two pieces of metal onto the cathode and anode of a large battery using two small magnets and threw it into a bowl of salt water. Immediately, I could see the reaction taking place. I don't quite understand every detail of it, but it is very interesting!

I left it there for a few hours, until the water turned into this weird, green gunk. I then took the battery out, poured the green gunk and water into a glass jar and heated it on a pan on medium heat for several hours.

All of the water evaporated and I scooped what looked like a grey sludge onto a glass plate and popped it into the microwave for one minute to evaporate the remaining water.

What I am left with is a mustard colored powder. It looks almost exactly like this:


I am not sure what kind of metal was used, but I assume it was either iron or steel. What I think I have made is some kind of iron oxide--exciting!

I am hoping to get some approval on this. Hopefully someone more experienced than I can validate this claim and maybe even tell me what kind of iron oxide this is.

I want to make some thermite for a spectacular youtube experiment, and I think this is a pretty cool way of making iron oxide, if that is what I have done.

Thank you. I am a chemistry major at university and I love chemistry and physics!

[Arkcon]

So, I attached two pieces of metal onto the cathode and anode of a large battery using two small magnets

I wouldn't have used magnets, I would have instead used conductive, insulated wire but, OK.

and threw it into a bowl of salt water.

You could have kept the battery out with wire, then used the battery again.

Immediately, I could see the reaction taking place. I don't quite understand every detail of it, but it is very interesting!

Shine on you crazy diamond.

I left it there for a few hours, until the water turned into this weird, green gunk. I then took the battery out, poured the green gunk and water into a glass jar and heated it on a pan on medium heat for several hours.

Nice.  Gentle, patient heating is important.

All of the water evaporated and I scooped what looked like a grey sludge onto a glass plate and popped it into the microwave for one minute to evaporate the remaining water.

I wouldn't have done that, at least it didn't seem to arc and damage the magnetron.

What I am left with is a mustard colored powder. It looks almost exactly like this:


I am not sure what kind of metal was used, but I assume it was either iron or steel. What I think I have made is some kind of iron oxide--exciting!

Cool.

I am hoping to get some approval on this.

I don't like some of your choices of techniques, but still, nice idea

Hopefully someone more experienced than I can validate this claim and maybe even tell me what kind of iron oxide this is.

I'd start here:  http://en.wikipedia.org/wiki/Iron_oxide  You have 16 to choose from.

I want to make some thermite for a spectacular youtube experiment, and I think this is a pretty cool way of making iron oxide, if that is what I have done.

Yeah, we don't give the specifics for this reaction on this board, just so you know in advance.

Thank you. I am a chemistry major at university and I love chemistry and physics!

[Bionic Person]

It was very crude and messy. In fact, I really had no idea what I was doing or what I was making until the very end and I was like, what the heck did I just do? I figured it must be some kind of powdered metal, and then assumed it must be oxidized because of the color and smell. I assume it's oxidized iron, but I am not sure what kind of metal I used. Overall, I think it was a success.

The battery still works fine, though. I threw my phone battery in there with it, just for fun, and it still works fine as well.

[billnotgatez]

I would love a picture of your setup

[408]

Ghetto, yo.

Love it, but need more details before guessing what your yellow s#*$ is.  Was your "metal" even iron?


Or just mix it with powder Al (stoich for Fe2O3 should be close enough), stick some Mg ribbon in it and see if it goes. 

But I am guessing it is....Yellow iron oxide, lol.  Put it in the oven and crank it for a few hours.  Should knock out some water. 

PS: use copper wire, basic solution, you will get copper (II) hydroxide, which easily dehydrates to the oxide. 

[curiouscat]

A google image search  yields one iron oxide type with photos that very closely resemble what you have.

https://www.google.com/search?q=iron+oxide+photos

[Zyklonb]

First, test you "mystery metal" with a magnet to see if it is iron (sure other metals are magnetic, but that will narrow it down).
I doubt you made any pure oxide, I'm betting it was stainless steel. Green = nickel ions most likely.  There's lots of different oxidation states of iron, but only a few that can be made using electrolysis with an iron anode.
Can you upload a picture of your actual product? Rather than somthing that looks similar.

[Bionic Person]

I plan on repeating the experiment in a few weeks. I think the metal I used was probably steel, but wouldn't steel still produce iron oxide? I know it wasn't pure. There was weird stuff forming on the positive end of the battery. Both sides were rusted, but different colors. And, it was green at first, while it was still in the water, but after I evaporated the water it turned bright orange, like a mustard color.

I'm also unsure if iron oxide would maintain it's magnetism. I probably made some odd assortment of oxides. Next time I may just use the magnets.

[Zyklonb]

I'm also unsure if iron oxide would maintain it's magnetism

It depends on the oxidation state. Iron (III) oxide [AKA rust] is not magnetic. Iron (II,III) oxide (Fe₃O₄ [AKA Magnetite]) is, hence it's name, magnetic.
I'm not really sure of the other oxidation states, but I doubt you have anything else, so it's likely irrelevant.

I think the metal I used was probably steel, but wouldn't steel still produce iron oxide?

Yes. Steel contains (generally) only iron, carbon and on occasion small (>.1%)quantities of other transition metals (e.g. manganese, titanium, aluminum, copper etc.)

There was weird stuff forming on the positive end of the battery. Both sides were rusted, but different colors. And, it was green at first, while it was still in the water, but after I evaporated the water it turned bright orange, like a mustard color.

Green. Like I said, probably nickel, I know of no green iron oxides. Possibly copper, but I doubt it.
But test the METAL for magnetism. Not the oxide. It would be much easier to analysis the metal than the oxide. 

[Bionic Person]

It probably was nickel. I'll try to use steel next time. There was a weird bluish fog forming at the positive end. I tried to finger out what was going on in terms of a chemical equation, but I couldn't quite finger it out. I finger there's Na+ and Cl- ions and Fe+ and Fe- charges on either sides of the battery, and also H2O and maybe some H+ and OH- floating around. So H2 may be formed at the anode, maybe FeOH at the cathode. Maybe HCl at some point. I've got no idea.

[Zyklonb]

It probably was nickel.

Agreed.

I finger there's Na+ and Cl- ions and Fe+ and Fe- charges on either sides of the battery

I don't know what you mean by that. I can tell you there is no way any Fe^- ions are in solution.

also H2O and maybe some H+ and OH- floating around.

Yes of course there is water, but there won't be any hydroxide ions or hydronium ions because they would react immediately - just like any acid-base reaction.

So H2 may be formed at the anode

You mean the cathode?

maybe FeOH at the cathode.

That would be the anode.

Maybe HCl at some point.

Nope. HCl (aq) could never form under these conditions. Besides, it would react with iron hydroxide to make iron chloride hydrates and water.

[billnotgatez]

@Zyklonb
You might want to explain this

I can tell you there is no way any Fe- ions are in solution.

From WIKI

Iron(III) chloride
Solubility in water    74.4 g/100 mL (0 °C)[1]
92 g/100 mL (hexahydrate, 20 °C)

[Borek]

@Zyklonb
You might want to explain this

I can tell you there is no way any Fe- ions are in solution.

No such thing as Fe^-. What IS present in the solution are Fe²⁺ and Fe³⁺ cations.