3 P₂O₃ + 2 HClO₃ + 9 H₂O → 6 H₃PO₄ + 2 HCl

This is an oxidation-reduction (redox) reaction:

P₂O₃ is a reducing agent, HClO₃ is an oxidizing agent.

Reactants:

• P₂O₃
  • Names: Phosphorus trioxide , Phosphorus(III) oxide , Phosphorus sesquioxide ... show morePhosphorous oxide , Phosphorous anhydride , Tetraphosphorous hexoxide show less
  • Appearance: Colourless monoclinic crystals or liquid
• HClO₃
  • Names: Chloric acid , Chloric(V) acid , HClO3 ... show more[ClO2(OH)] , Chlorsäure , Chlorate show less
  • Appearance: Colourless solution
• 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

Products:

• 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.]
• HCl – Chlorane , Hydrogen chloride
  • Other names: Hydrochloric acid , M , Uriatic acid ... show moreHydronium chloride , Chlorhydric Acid , Hydrochloric acid gas , HCl , Anhydrous 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.]