5 HCl + NaNO₃ + Au → 2 H₂O + NaCl + NO + HAuCl₄

This is an oxidation-reduction (redox) reaction:

Au is a reducing agent, NaNO₃ is an oxidizing agent.

Reactants:

• HCl – Chlorane , Hydrogen chloride
  • Other names: Hydrochloric acid , Hydrochloric acid gas , HCl ... show moreAnhydrous hydrogen chloride , Hydrochloric acid, anhydrous , Aqueous hydrogen chloride , [Note: Often used in an aqueous solution.] show less
  • Appearance: Colorless, transparent liquid, fumes in air if concentrated ; Colorless gas ; Colourless compressed liquefied gas with pungent odour ; Colorless to slightly yellow gas with a pungent, irritating odor. [Note: Shipped as a liquefied compressed gas.]
• NaNO₃ – Sodium nitrate
  • Other names: Peru saltpeter , Soda niter , Cubic niter ... show moreNitric acid sodium salt (1:1) , Sodium saltpeter , Nitric acid, sodium salt , Nitrate of soda , Nitric acid monosodium salt , Sodium(I) nitrate (1:1) , Niter , Chile saltpeter show less
  • Appearance: White powder or colorless crystals ; Colourless hygroscopic crystals
• Au
  • Names: Gold , Au , Element 79 , Aurum

Products:

• 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
• NaCl – Sodium chloride
  • Other names: Salt , Table salt , Common salt ... show moreNaCl , Broncho saline show less
  • Appearance: Colorless cubic crystals
• 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.]
• HAuCl₄
  • Names: Chloroauric acid , Hydrogen tetrachloroaurate , Chlorauric acid ... show moreAurochloric acid , Aurate(1−) , Tetrachloro- , Hydrogen , (SP-4-1)- , Hydrogen aurichloride show less
  • Appearance: Orange-yellow needle-like crystals | hygroscopic