Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: JC Denton on March 21, 2004, 05:44:21 PM
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Hi,
I was wondering how to make large quantities of Iron Oxide in a short time, could someone give me a detailed description on how to do it? A few places suggested electrolysis...is this the best way to do it?
thanks alot, JC
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Are you just trying to make rust?
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U really sound like making rust... spray some water on an iron rod and leave it inside a humid environment. It will rust 8)
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Which one? There are three at least quite common. They can be formed during heating iron turnings in the air for some time.
AWK
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Thanks, yeah I just wanted some rust for a experiment, at the moment I left some nails connected to a DC adapter in a jar of salty water, there has been quite a reasonable amount of rust made already thankfully :)
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i still think heating iron filing in air is better than spraying water on iron rods or soaking nails in water.. the wet rust does kinda get very messy..
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speaking of iron oxide, is there an easy way to get rid of that oxygen atom and return it back to regular iron? without using a thermite type reaction, which I think is called a displacement reaction?
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thermite would be the only way I know.
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Without digging up the math behind it, is this correct:
You can put iron and oxygen together because its thermodynamically delicious, but trying to reverse the process requires a ton of energy (magnesium fire) to counter the energy of the bond formed when the iron oxidized.
Sound good? layman's terms make things so much easier to understand for me.
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Thermodynamically one would expect the opposite to occur. One of the tenets of thermodynamics is that the entropy of the universe always incrases. So if you took iron oxide and turned it into iron and oxygen; that means you took one tthing and made 2 things from it. Thus increasing the entropy of the universe.
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good point, but once you've got the bond, there should be enough energy holding it together to tell off thermodynamics as opposed to the bond with say.. triiodide stuff. obviously it can't be thermodynamically sound for iron and oxygen to fall apart, because iron will oxidize just by sitting in a humid environment. why is that then? I mean, I understand the point about entropy, but not just iron can oxidize and stay that way. aluminum oxide for instance. so why DO things oxidize if it goes against the idea of entropy?
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The easy and clean way to make rust is just to shove iron wool in a bottle and fill it with H2O2,
The 9% conc. works pretty well, but I'm sure it would be done in no time with 30-45% peroxide, I wonder if oxyclean type bleaches would work, they contain sodium peroxycarbonate which liberates H2O2 in aq. solution ;D
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well.. over where i am.. i can only get the crap 3% H2O2 solution. which is. quite sad.. wonder if the pharmacist has some higher concentration H2O2 hidden in that cupboard behind the counter..
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I purchased a few pounds of iron oxide at a ceramic supply shop for a reasonable price.
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The 3% H2O2 will work too, you just have to leave the iron wool in to soak, and use more peroxide thats all, it seems to be about the cheapest way to make rust anyway :)
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good point, but once you've got the bond, there should be enough energy holding it together to tell off thermodynamics as opposed to the bond with say.. triiodide stuff. obviously it can't be thermodynamically sound for iron and oxygen to fall apart, because iron will oxidize just by sitting in a humid environment. why is that then? I mean, I understand the point about entropy, but not just iron can oxidize and stay that way. aluminum oxide for instance. so why DO things oxidize if it goes against the idea of entropy?
Entropy isn't the only thing that determines if a reaction will happen. Overall, you have to look at the Gibbs Free Energy for a reaction. A negative ?G will mean that a reaction is favored to happen, and a positive one indicates that it isn't likely/won't happen.
?G = ?H -T?S
So a reaction with a highly negative ?H and a highly positive ?S is favored to go ahead. So in a reaction where the entropy decreases, if the enthalpy is highly negative, then it will be favored to proceed.