HNO2 + 2 SO2 + 3 H2O → NH2OH + 2 H2SO4

This is an oxidation-reduction (redox) reaction:

2 SIV - 4 e- → 2 SVI (oxidation)

NIII + 4 e- → N-I (reduction)

SO2 is a reducing agent, HNO2 is an oxidizing agent.

Reactants:

  • HNO2 – Nitrous acid source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02, Hydroxidooxidonitrogen source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Other names: HNO2 source: wikidata, accessed: 2019-09-02, [NO(OH)] source: wikidata, accessed: 2019-09-02, Nitrosyl hydroxide source: wikidata, accessed: 2019-09-02, Dioxonitric acid source: wikidata, accessed: 2019-09-02
    • Appearance: Pale blue solution source: wikipedia, accessed: 2019-09-27
  • SO2 – Sulfur dioxide source: wikipedia, accessed: 2019-09-28source: wikidata, accessed: 2019-09-02source: NIOSH NPG, accessed: 2019-09-02
    • Other names: Sulfurous anhydride source: wikipedia, accessed: 2019-09-28source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Sulphur dioxide source: ICSC, accessed: 2019-09-04source: wikidata, accessed: 2019-09-02, Sulfurous acid anhydride source: wikidata, accessed: 2019-09-02source: NIOSH NPG, accessed: 2019-09-02
    • Appearance: Colorless gas source: wikipedia, accessed: 2019-09-28; Colourless gas or compressed liquefied gas with pungent odour source: ICSC, accessed: 2019-09-04; Colorless gas with a characteristic, irritating, pungent odor. [Note: A liquid below 14°F. Shipped as a liquefied compressed gas.] source: NIOSH NPG, accessed: 2019-09-02
  • H2O – Water, 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

Products:

  • NH2OH – Hydroxylamine (only preselected) source: wikipedia, accessed: 2019-09-27
    • Other names: Hydroxylamine source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Azinous acid source: wikipedia, accessed: 2019-09-27, Aminol source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Appearance: Vivid white, opaque crystals source: wikipedia, accessed: 2019-09-27; Very hygroscopic white needles or flakes source: ICSC, accessed: 2019-09-04
  • H2SO4 – Sulfuric acid source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-07source: NIOSH NPG, accessed: 2019-09-02
    • Other names: Oil of vitriol source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-07source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, Sulfuric acid, concentrated (> 51% and < 100%) source: ICSC, accessed: 2019-09-04, H2SO4 source: wikidata, accessed: 2019-09-07
    • Appearance: Clear, colorless liquid source: wikipedia, accessed: 2019-09-27; Odourless colourless oily hygroscopic liquid source: ICSC, accessed: 2019-09-04; Colorless to dark-brown, oily, odorless liquid. [Note: Pure compound is a solid below 51°F. Often used in an aqueous solution.] source: NIOSH NPG, accessed: 2019-09-02