baconaut
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"Bumping" Mg from MgSO4
Hello, I am going to attempt an experiment where I make a solution of MgSO4 and water and attempt the "bump" the Magnesium out and replace it with
another metal, like iron. I did this with CuSO4 and Fe in class, and want to know if what I am attempting would work.
Am I wrong to assume that this would work with other metals, and could someone please explain to me why the sulfate "preferred" the iron instead of
the copper, so I can find another suitable metal to try this with, if any?
Not trying to get you guys to do my homework, I'm doing this independent of school and want to LEARN! woo...
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evil_lurker
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It has to do with the electrical potential of the metals and yes it does work with certain other metals.
However, it is impossible to get elemental magnesium this way because magnesium being an alkali metal it will instantly react with the water forming
magnesium hydroxide.
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Nicodem
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| Quote: | Originally posted by evil_lurker
However, it is impossible to get elemental magnesium this way because magnesium being an alkali metal it will instantly react with the water forming
magnesium hydroxide. |
It is not about being an alkali metal, it is about the redox potentials and their difference. Magnesium does indeed react with water when finely
divided (but when in pieces it does so very slowly). However this is not the reason why one can not reduce magnesium cations to magnesium metal with
iron metal. The reason is simply in that the redox potential of the Fe -> Fe(2+) + 2e(-) reaction is not high enough to drive the Mg(2+) + 2e(-)
-> Mg reaction. It is the same reason in that one can not electrolyze water at room temperature when using, for example 1V potential between the
electrodes, but can do so when using 3V.
Reading material for beginners:
AN INTRODUCTION TO REDOX EQUILIBRIA and ELECTRODE POTENTIALS
THE ELECTROCHEMICAL SERIES
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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12AX7
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I suppose in theory you might get the reaction MgO + Fe = FeO + Mg(g), but MgO is a really fucking stable compound, I don't see it working.
Everything would have to melt together at the very least, and vacuum would be needed to pull off the magnesium vapor. Magnesium thermite goes
strongly to the left in the above equation, and gets very hot in the process (2500C+). You would have to get still hotter than that to produce any
results. Even carbon has trouble reducing magnesium, as Mg(g) + CO(g) = MgO(s) + C(s). You can heat carbon and magnesia, but it'll only condense the
same thing unless you cool the (rather hot) gasses quickly, subliming the Mg metal before it can react with the CO. Similarly for aluminum, which
forms a carbide as well.
Alkali metal oxides can be reduced by alkaline earths, aluminum and carbon. Most such reactions produce alkali vapor. You might react an alkali
metal with an alkaline earth chloride, where ionic behavior is stronger than in oxides.
Tim
[Edited on 10-27-2006 by 12AX7]
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Jdurg
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| Quote: | Originally posted by evil_lurker
It has to do with the electrical potential of the metals and yes it does work with certain other metals.
However, it is impossible to get elemental magnesium this way because magnesium being an alkali metal it will instantly react with the water forming
magnesium hydroxide. |
Also, Magnesium is not an alkali metal. It's an alkaline-earth metal which is distinctly different. You'll have a tough time getting Mg to react
with water at room temperature, but not so with an alkali.
\"A real fart is beefy, has a density greater than or equal to the air surrounding it, consists of the unmistakable scent of broccoli, and usually
requires wiping afterwards.\"
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