How is Magnesium Obtained?
Magnesium can be obtained through several commercial processes and would not be normally created in labs due to its ready availability. Seawater for instance contains a massive amount of magnesium. This compound can be recovered as magnesium chloride, MgCl2 through a reaction with CaO.
CaO + H2O --> Ca2+ + 2OH-
Mg2+ + 2OH- --> Mg(OH)2
Mg(OH)2 + 2HCl --> MgCl2 + 2H2O
Electrolysis of molten MgCl2 affords magnesium as a liquid which is poured off and chlorine gas.cathode: Mg2+(l) + 2e- --> Mg anode: Cl-(l) --> 1/2Cl2 (g) + e-
The other method used to produce magnesium uses dolomite (MgCa(CO3)2) and does not deal with electrolysis as the earlier example did. This is "calcined" by heating to form calcined dolomite, MgO.CaO, and is reacted with a ferrosilicon alloy.
2[MgO.CaO] + FeSi --> 2Mg + Ca2SiO4 + Fe
http://www.webelements.com/webelements/elements/text/Mg/key.html
Terms:
Electrolysis
Calcined
Ferrosilicon Alloy
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