What can be used instead of magnesium to make silicon from sand (in lab)? [closed]








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I found [this post](https://www.popsci.com/diy/article/2005-10/making-silicon-sand/) talking about making silicon from sand. They mixed magnesium with sand and then burn them then it create silicon and magnesium oxide. And my question is what can we use instead of magnesium in this experiment (something easier to find at home) to make silicon from sand? Thanks in advance!


P/S: I want to figure out other ways to do this before buying magnesium online :) Just want to try this at home with easy-to-find (at home) chemicals.


[This post](https://chemistry.stackexchange.com/questions/24649/is-it-possible-to-extract-magnesium-from-epsom-salt) shows how to make magnesium from magnesium oxide (which I can found in my batteries) but it need silicon to do that :)




If you really are interested in making your own silicon, [Wikipedia](https://en.wikipedia.org/wiki/Silicon) offers several methods used industrially. None is easy; all require high temperature operation, with furnaces more likely to be seen in an industrial environment than in a typical chemical laboratory, let alone at home.


* Carbothermal reduction. Silicon dioxide (silica) is reduced by elemental carbon (coke) in an electric arc furnace. Excess silica is used to prevent contamination with silicon carbide which can also form. Usually this process is not used to make silicon as such, but done with iron also included to make **ferrosilicon**, used in steelmaking. The ferrosilicon may be used to reduce magnesium oxide (also not trivial in a laboratory setting), as the iron does not interfere with that reaction.
* Aluminothermic reduction. Silica is reduced by aluminum metal, as described by Maurice in his answer. Silicon produced in this way is suitable for use in chemical processes. The reaction given by both WP and Maurice is likely a simplified description, as ternary aluminum-silicon oxides might also be formed. This makes the production of silicon more favorable thermodynamically, but takes up some of the silicon in the ternary oxides. As Maurice points out, the aluminum has to be molten. So as with the carbothermic reduction, you need a furnace capable of achieving high enough temperature.
* Special methods are needed to generate semiconductor-grade silicon. These actually do not use silica as the silicon source; instead, volatile compounds that can be pre-purified by fractional distillation, such as $\ce{SiCl4}$, are employed. Additional purification by zone melting is needed to get the purity needed for semiconductor use.


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Silica $\ce{SiO2}$ can be reduced at high temperature into silicium with aluminum powder, in a reaction like : $\ce{4 Al + 3 SiO2 -> 2 Al2O3 + 3 Si}$. This reaction is exothermic by $\pu{\Delta H = -185 kJ mol^{-1}}$ and exoergic by $\pu{\Delta G° = -178 kJ mol^{-1}}$ which becomes $\pu{\Delta G = -165 kJ mol^{-1}}$ at $\pu{1000 K}$. It was sometimes used to prepare metallic silicium. But this reaction is rather difficult to start, as it occurs only with liquefied aluminum, so that the mixture must be pre-heated to the melting point of aluminum ($\pu{659°C}$ )


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