Electrolysis of iron

[airkyd]

ok, i want to get some rusk. so i get a nail , connect to my 12 volt power supply. then i stick the positive and negative ends into some salt water ( tap water + cooking salt) first i get a layer of orange precipitate forming at the bottom( common rust) . but then i get a layer of green/white precipitate???? wat the hell is this??? i have heard that come iron oxide goes strangr colours but i want to conform that its rust. or it another oxide from the other composite in the nail???? any one got any ideas wa happening here?

[woelen]

There are two explanations:

1) A lower hydroxide of iron is formed. Iron (II) hydroxide is green/white, iron (III) hydroxide is orange/brown.

2) The nail does not consist of pure iron, but another metal is involved. When the iron is used up, then the other metal goes in solution. Many metal hydroxides are white. Due to impurities this may look off-white.

[airkyd]

take a look at these , tell me wat you think???

 

lol, im a student can afford the proper stuff, a old mobile phone charger for the powersupply, a beer glass for the container , lol

 

http://img477.imageshack.us/my.php?image=10002399tu.jpg

 

http://img477.imageshack.us/my.php?image=10002415gf.jpg

 

The blue/green stuff could be lead oxide, right?? being a nail , i expect lead to be a composite if any ...

[xeluc]

AHA! I know what the blue stuff on top is. If you notice on your first picture, you have the nail in the solution, but there is also copper wire exposed. This means that Copper is also oxidized into solution. the Light blue precipitate on top is Most probably Cu(OH)2 (Copper Hydroxide). As for the dark green stuff. I have also seen this when electrolising decently clean steel wool. I agree with Woelen, that it is a different kind of Iron hydroxide.

 

Keep in mind that the brown stuff you called rust is actually Iron hydroxide. Apon drying it rearranges to become Iron Oxide So in the end, it's all the same.

 

ALSO, I would think that no iron compound you could make is orange.... I'd say this is Copper (I) Oxide, as I have also made this, and have tested it and it tested positive for Cu Ions. what I don't understand is how you got this orange prec. first. You would think that the Iron would be oxidized first as Woelen said. Also, I dont understand why both Cu(OH)2 and Cu2O were formed...

 

@Woelen: Does the green Hydroxide also decompose? My powersupply died so I can;t test this myself.

 

 

 

Lol, does the picture say "supasweet" on that cylinder? haha.. sorry

[airkyd]

 

@Woelen: Does the green Hydroxide also decompose? My powersupply died so I can;t test this myself.

 

 

 

Lol' date=' does the picture say "supasweet" on that cylinder? haha.. sorry[/quote']

 

 

yup supasweet diabetic sweeteners } no, i think that the dark green stuff formed when i switch nail with the node. as for teh over rall reaction i dont know wat to do now??? still want to make that iron oxide. hmmm wat should i cover the other node? to make sure its no exposed? wat is copper oxide good for? any thing?

[akcapr]

I really like that beaker you are conducting it in lol

[xeluc]

You should use the search function.....

Me and Akcapr already gave out lot's of advice on rust synthesis. Check Here.

[airkyd]

how can i seperate the Fe(OH)2 from the Cu(OH)2 ??? rust is magnetic , isn't it?

[xeluc]

i know magnetite it, I dont' know about Hematite. Dude, it doesn't look like you have a whole lot anyhow, just scrap it and do it over, but make sure no copper is showing on your anode and you'll be fine.

[woelen]

@xeluc: Fe(OH)2 does not decompose, it is very sensitive to earial oxidation. A little bit like the problems you have with making nice CuCl. Have a look at this:

 

http://woelen.scheikunde.net/science/chem/solutions/fe.html

 

Look at the section for oxidation state +2 and quite some info is given on Fe(OH)2. Also look at the nice light green color of pure Fe(OH)2 and the color of the partially oxidized stuff.

 

 

@airkyd: The materials you use are impure. You have an iron nail and copper wire immersed in the liquid at the same time. As Xeluc already stated, you must assure that ONLY iron is touching the liquid. So, wrap some copper wire around the head of the nail and only dip the lower part of the nail into the liquid. Then start over again and show us again what kind of precipitates you obtain.

[P-man]

Would you therefore need a pure iron nail?

[woelen]

Would you therefore need a pure iron nail?

Best is to use a pure iron nail. If there is some zinc in it, that does not bother. After electrolysis you can easily get rid of the zinc hydroxide by dissolving it in excess sodium hydroxide. Most other metal impurities also result in formation of impure iron hydroxide.

 

Why not go to an electronics shop, where they sell electronic components? At such places they also sell almost pure FeCl3.6H2O for etching purposes. From that you can easily make a lot of fairly pure Fe(OH)3 by simply adding solution of sodium hydroxide to a solution of FeCl3 in water. The product Fe(OH)3 will contain a little chloride, but that does no real harm. On heating it will be driven off as HCl.

[YT2095]

if you MUST use copper wire to attatch to the nail, then dip that end in wax, it`ll provide some protection against splashes when the soln fizzes, bubble gum works just as well

 

if you use Steel nails and do it properly you should get a tiny amount of a Black powdery PPT also, that`s actualy the Carbon coming out of the steel! (perfectly harmless to the reaction though)

[akcapr]

What i did is i smothered the copper in hot glue allowing the iron too peek out.

[P-man]

if you MUST use copper wire to attatch to the nail, then dip that end in wax, it`ll provide some protection against splashes when the soln fizzes, bubble gum works just as well

I hadn't thought of that. I guess it's the best way to prevent the copper wire from getting into the reaction. But why use copper wire. Isn't there something else out there that wouldn't react in the experiment?

 

What i did is i smothered the copper in hot glue allowing the iron too peek out.

Man, some people really do think before thay do stuff. I would have never thought of doing that. Maybe it's because I have no common sense.

[xeluc]

if you MUST use copper wire to attatch to the nail' date=' then dip that end in wax, it`ll provide some protection against splashes when the soln fizzes, bubble gum works just as well

 

if you use Steel nails and do it properly you should get a tiny amount of a Black powdery PPT also, that`s actualy the Carbon coming out of the steel! (perfectly harmless to the reaction though)[/quote']

 

Maybe it should be stressed that even when this is done, you should still try your best to keep the copper out of solution. Even if it is protected; If everything is in the water, the metal underneath the wax could corrode, breaking your seal. YT hinted at this and Woelen went and said it, heh..

[YT2095]

But why use copper wire. Isn't there something else out there that wouldn't react in the experiment?

 

Indeed, why use copper wire at all near the solution?

sadly there aren`t many sources of iron or steel wire that doesn`t have a coating of some sort over it, from fencing wire to simple coat hangers.

But, you Could go down to your local hardware shop and buy a metre or two of 5mm bar stock instead

or even use Rebar if you want to do this on a large scale!

[kyle32123]

Sorry to bring up this old topic but im trying to make some Fe2O3 and i just needed a little help.

 

I got a beaker and added a teaspoon of NaCl. I used nails as the electrodes and my prower source was a 15V DC Converter. The Copper wire was not touching the solution at all only the nails, i used 2 nails, one on anode and 1 on cathode.

I let it sit for a while and i was left wiht a red brown foam on top and a real dark brown almost black precipitate on the bottom. The black precipitate was comming of the Positive. Hydrogen was comming off the other.

 

Is this dark brown/black precipitate Iron (lll) Hydroxide? which i can let dry and turn to Fe2O3?

 

I took the beaker and took all its containments and dumped them in a bottle and took out most of the water and i tried to boil off the water but i ran out of time so i will let it sit and evaporate the water.

 

Is this correct and will i get rust?

[woelen]

Pure rust is not black, but brown/red. I think that the foam at the surface indeed contains rust (or better: ferric hydroxide). The lower black precipitate undoubtedly will contain quite some rust, but it is heavily contaminated with something else. Maybe carbon from the steel nails, maybe some other metal oxide, maybe even a mix of iron (II) and iron (III) hydroxide. The problem with this type of experiments is that the starting materials are so impure. An ordinary nail contains iron, but also a LOT of other metals, carbon, even small amounts of phosphorous, as phosphide.

 

Also keep in mind that 15 V DC is way too much for electrolysis purposes. Try a 5 V DC power supply, with a decent current output. The current determines how much chemicals are formed, the voltage determines only which reactions will occur. A high overvoltage only results in heating up of the liquid. E.g. when the reaction requires 3 V, and 15 V is applied and the current is 1 A, then 3 W of power are used for the chemical reaction, and 12 W of power is consumed and heats up all things.