JCM83 - 6-1-2011 at 21:06
Hi sciencemadness, I'm John, I'm a budding chemistry teacher. My background is bio and psych with a minor in chem, so I'm finding that since I managed
to snag a job teach HS chem in a bad economy, I intend to keep it. I will ask you guys questions that you may find unbecoming of a chem teacher, but
hey- that's how I'll learn, right?
Look at this:
http://www.youtube.com/watch?v=faorfmRkCv0
Dude uses NaOH + MG to get Na metal. 
How does that work? My understanding was that sodium is more reactive, and is a stronger reducing agent, than magnesium. Larger atomic radius, lower
electronegativity, so how'd it end up stealing all the electrons in this reaction?
(Does it have something to do with the reaction being performed in air instead of water?)
Thanks.
hkparker - 6-1-2011 at 21:56
2Mg + 2NaOH = 2MgO + 2Na + H2
It works because its thermodynamically favorable, despite the fact that the reduction potentials are counter intuitive. And its very
thermodynamically favorable, the reaction produces extreme heat, Ive done it several times but couldn't get the sodium that pure from the remaining
magnesium oxide. Hope that helps!
condennnsa - 6-1-2011 at 22:39
Apparently, the products of this is a high percentage of sodium hydride.
JCM83, have a look at the Make potassium thread, they do the same thing, but in a controlled manner in organic solvent, and with excellent results
hkparker - 6-1-2011 at 22:48
That would probably be the product in an organic solvent but in this reaction the heat is so great it decomposes any sodium hydride formed (decomp
point 800C). Haven't calculated the exact change in enthalpy but I know its suppost to be over 1000C