Preparation of magnesium silicide (Mg2Si) and silane (SiH4)

This demonstration shows the synthesis of magnesium silicide by the spectacular combustion of magnesium with silica (sand), and subsequently the reaction of the prepared silicide with acid, which produces silane gas, that spontaneously ignites in air.
Summary reactions of the involved processes:
Preparation of magnesium silicide: 4Mg + SiO2→ 2MgO + Mg2Si
Preparation of silane: Mg2Si + 4HCl → 2MgCl2 + SiH4
Combustion of silane: SiH4 + 2O2 → SiO2 + 2H2O

I suppose one could change the mixture of sand and silica gel for the same amount of ground cat litter, but I did not try yet...
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Příprava silicidu hořečnatého, syntéza silanu, sampozápalný plyn, silan, SiH4.
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