7 H2O + 4 HNO3 + 3 P2O3 4 NO + 6 H3PO4

This is an oxidation-reduction (redox) reaction:

6 PIII - 12 e- 6 PV (oxidation)

4 NV + 12 e- 4 NII (reduction)

P2O3 is a reducing agent, HNO3 is an oxidizing agent.

Reactants:

  • H2OWater, oxidane source: wikipedia, accessed: 2019-09-27
    • Other names: Water (H2O) source: wikipedia, accessed: 2019-09-27, Hydrogen hydroxide (HH or HOH) source: wikipedia, accessed: 2019-09-27, Hydrogen oxide source: wikipedia, accessed: 2019-09-27
    • Appearance: White crystalline solid, almost colorless liquid with a hint of blue, colorless gas source: wikipedia, accessed: 2019-09-27
  • HNO3Nitric acid source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: NIOSH NPG, accessed: 2019-09-02
    • Other names: Aqua fortis source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: NIOSH NPG, accessed: 2019-09-02, Spirit of niter source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02, Eau forte source: wikipedia, accessed: 2019-09-27
    • Appearance: Colorless, yellow or red fuming liquid source: wikipedia, accessed: 2019-09-27; Colourless-to-yellow liquid with pungent odour source: ICSC, accessed: 2019-09-04; 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.] source: NIOSH NPG, accessed: 2019-09-02
  • P2O3
    • Names: Phosphorus trioxide source: wikipedia, accessed: 2019-09-27, Phosphorus(III) oxide source: wikipedia, accessed: 2019-09-27, Phosphorus sesquioxide source: wikipedia, accessed: 2019-09-27
    • Appearance: Colourless monoclinic crystals or liquid source: wikipedia, accessed: 2019-09-27

Products:

  • NONitrogen monoxide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: NIOSH NPG, accessed: 2019-09-02, Oxidonitrogen(•) (additive) source: wikipedia, accessed: 2019-09-27
    • Other names: Nitric oxide source: wikipedia, accessed: 2019-09-27source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02source: wikidata, accessed: 2019-09-02, Nitrogen(II) oxide source: wikipedia, accessed: 2019-09-27, Nitric oxide (radical) source: wikidata, accessed: 2019-09-02
    • Appearance: Colourless gas source: wikipedia, accessed: 2019-09-27; Colourless compressed gas source: ICSC, accessed: 2019-09-04; Colorless gas. [Note: Shipped as a nonliquefied compressed gas.] source: NIOSH NPG, accessed: 2019-09-02
  • H3PO4
    • Names: Phosphoric acid source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, Orthophosphoric acid source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, Phosphoric(V) acid source: wikidata, accessed: 2019-09-02
    • Appearance: Hygroscopic colourless crystals source: ICSC, accessed: 2019-09-04; Thick, colorless, odorless, crystalline solid. [Note: Often used in an aqueous solution.] source: NIOSH NPG, accessed: 2019-09-02