Reaction of Silicon with acids 

Silicon does not react with most acids under normal conditions but is dissolved by hydrofluoric acid, HF, to form fluorosilicic acid, a reaction apparently driven by the stability of the Si(IV) fluoride complex [SiF₆]^2-.

Si(s) + 6HF(aq) →  2H₂(g) +H₂SiF₆ (aq) (fluorosilicic acid)