3 Si (s) + 12 HF (aq) + 4 HNO₃ (aq) → 3 SiF₄ (g) + 4 NO (g) + 8 H₂O (l)

This is an oxidation-reduction (redox) reaction:

Si is a reducing agent, HNO₃ is an oxidizing agent.

Reactants:

• Si
  • Names: Silicon , Si , Element 14 ... show moreElemental silicon , [Note: Does not occur freely in nature, but is found in silicon dioxide (silica) and in various silicates.] show less
  • Appearance: Steel-grey crystals or black-to-brown amorphous powder ; Black to gray, lustrous, needle-like crystals. [Note: The amorphous form is a dark-brown powder.]
• HF – Fluorane
  • Other names: Hydrofluoric acid , Hydrogen fluoride , Fluorhydric acid ... show moreHydronium fluoride , Hydrofluoric acid (70% aqueous solution) , Hydrofluoric acid, anhydrous , Anhydrous hydrogen fluoride , Aqueous hydrogen fluoride , HF-A show less
  • Appearance: Colorless solution ; Colourless gas or colourless liquid (below 19.5 °C) ; Colourless gas or colourless fuming liquid with pungent odour ; Colourless fuming liquid with pungent odour ; Colorless gas or fuming liquid (below 67°F) with a strong, irritating odor. [Note: Shipped in cylinders.]
• HNO₃ – Nitric acid
  • Other names: Aqua fortis , Spirit of niter , Eau forte ... show moreHydrogen nitrate , Acidum nitricum , Nitric acid (> 70% in water) , Fuming nitric acid , Engravers acid , HONO2 , Red fuming nitric acid , RFNA , White fuming nitric acid (WFNA) show less
  • Appearance: Colorless, yellow or red fuming liquid ; Colourless-to-yellow liquid with pungent odour ; Colorless, yellow, or red, fuming liquid with an acrid, suffocating odor. [Note: Often used in an aqueous solution. Fuming nitric acid is concentrated nitric acid that contains dissolved nitrogen dioxide.]

Products:

• SiF₄ – Tetrafluorosilane , Silicon tetrafluoride
  • Other names: Silicon fluoride , Fluoro acid air , Perfluorosilane
  • Appearance: Colourless gas, fumes in moist air ; Colourless gas with pungent odour
• NO – Nitrogen monoxide , Oxidonitrogen(•) (additive)
  • Other names: Nitric oxide , Nitrogen(II) oxide , Nitric oxide (radical) ... show moreMononitrogen monoxide , (.)NO , EDRF , Nitrogen monooxide , [NO] , Oxido de nitrogeno(ii) , NO(.) , Oxido nitrico , Stickstoff(ii)-oxid , NO , Oxyde azotique , Oxyde nitrique , Stickstoffmonoxid , Nitrosyl , (NO)(.) , Monoxido de nitrogeno , Endothelium-derived relaxing factor , Nitroxide radical , Nitroxyl , Nitrosyl radical , Hydroxyamine , Nitrogen oxide , Nitrogen protoxide , Nitrosyl hydride , Nitric Oxide show less
  • Appearance: Colourless gas ; Colourless compressed gas ; Colorless gas. [Note: Shipped as a nonliquefied compressed gas.]
• H₂O – Water, oxidane
  • Other names: Water (H2O) , Hydrogen hydroxide (HH or HOH) , Hydrogen oxide ... show moreDihydrogen monoxide (DHMO) (systematic name) , Hydrogen monoxide , Dihydrogen oxide , Hydric acid , Hydrohydroxic acid , Hydroxic acid , Hydrol , Μ-oxido dihydrogen , Κ1-hydroxyl hydrogen(0) show less
  • Appearance: White crystalline solid, almost colorless liquid with a hint of blue, colorless gas