2 P (s) + H₂ (g) + 4 HNO₃ (aq) → 4 NO (g) + 2 H₃PO₄ (aq)

This is an oxidation-reduction (redox) reaction:

P is a reducing agent, H₂ is a reducing agent, HNO₃ is an oxidizing agent.

Reactants:

• P
• H₂
  • Names: Dihydrogen , Hydrogen , H2 ... show moreH₂ , Molecular hydrogen gas , Hydrogen gas , Hydrogen molecule , Molecular hydrogen show less
  • Appearance: Odourless colourless compressed gas
• 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:

• 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.]
• H₃PO₄
  • Names: Phosphoric acid , Orthophosphoric acid , Phosphoric(V) acid ... show moreWhite phosphoric acid , [PO(OH)3] , H3PO4 , E338 , Phosphoric acid (aqueous) show less
  • Appearance: Hygroscopic colourless crystals ; Thick, colorless, odorless, crystalline solid. [Note: Often used in an aqueous solution.]