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Reactions of Silicon
Reactions with water
A surface layer of oxide makes silicon unreactive to water and steam.
Reactions with air
Due to a thin layer of oxide on a sample of silicon it will not react with oxygen below temperatures of 900°C, above this the reaction with oxygen gives silicon dioxide.
  Si(s) + O2(g)SiO2(s)
At temperatures above 1400°C the silicon will react with nitrogen to give silicon nitrides.
  2Si(s) + N2(g)2SiN(s)
  3Si(s) + 2N2(g)Si3N4(s)
Reactions with halogens
Silicon reacts vigorously with all the halogens to form tetrahalides, the reaction with fluorine takes place at room temperature, the others require heating over 300°C.
  Si(s) + 2F2(g)SiF4(g)
  Si(s) + 2Cl2(g)SiCl4(g)
  Si(s) + 2Br2(l)SiBr4(l)
  Si(s) + 2I2(l)SiI4(s)
Reactions with acids
Under normal conditions silicon does not react with most acids, but is dissolved by hydrofluoric acid.
  Si(s) + 6HF(aq)[SiF6]2-(aq) + 2H+(aq) + 2H2(g)
Reactions with bases
Silicon is attacked by bases such as aqueous sodium hydroxide to give silicates.
  Si(s) + 4NaOH(aq)[SiO4]4-(aq) + 4Na+(aq) + 2H2(g)
 
Reduction Potentials
Balanced half-reaction E0 / V
SiO2(s) + 4H+ + 4e-Si(s) + 2H2O -0.86
SiO32- + 6H+ + 4e-Si(s) + 3H2O -0.455
HSiO3- + 5H+ + 4e-Si(s) + 3H2O -0.632
H2SiO3 + 4H+ + 4e-Si(s) + 3H2O -0.780
SiO2(s) + 8H+ + 8e-SiH4(g) + 2H2O -0.377
SiO32- + 10H+ + 8e-SiH4(g) + 3H2O -0.176
HSiO3- + 9H++ + 8e-SiH4(g) + 3H2O -0.265
H2SiO3 + 8H+ + 8e-SiH4(g) + 3H2O -0.339
Si(s) + 4H+ + 4e-SiH4(g) +0.102
SiF62- + 4e-Si(s) + 6F- -1.2