2 NO (g) + O₂ (g) → 2 NO₂ (l)

This is an oxidation-reduction (redox) reaction:

NO is a reducing agent, O₂ is an oxidizing agent.

Reactants:

• 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.]
• O₂
  • Names: Dioxygen , Oxygen , Oxygen (liquefied) ... show moreO2 , O₂ , Oxygen gas , Molecular oxygen , Oxygen, refrigerated liquid , LOX , Liquid oxygen show less
  • Appearance: Odourless compressed gas ; Liquefied gas. colourless-to-blue extremely cold liquid

Products:

• NO₂ – Nitrogen dioxide
  • Other names: Nitrogen(IV) oxide , Deutoxide of nitrogen , Nitrogen peroxide ... show moreNO2 , NO2(.) , Dinitrogen tetroxide (see notes) , Nitrogen tetroxide , Dinitrogen tetroxide show less
  • Appearance: Brown gas ; Reddish-brown gas or brown or yellow liquid with pungent odour ; Yellowish-brown liquid or reddish-brown gas (above 70°F) with a pungent, acrid odor. [Note: In solid form (below 15°F) it is found structurally as N2O4.]