4 NH3 (aq) + 3 SeO2 (aq) → 6 H2O (l) + 2 N2 (g) + 3 Se (s)

This is an oxidation-reduction (redox) reaction:

3 SeIV + 12 e- → 3 Se0 (reduction)

4 N-III - 12 e- → 4 N0 (oxidation)

SeO2 is an oxidizing agent, NH3 is a reducing agent.

This is a precipitation reaction: Se is the formed precipitate.

This is a gas evolution reaction, N2 is the formed gas.

Reactants:

  • NH3
    • Names: Ammonia source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: NIOSH NPG, accessed: 2019-09-02, Azane (only intended for use in naming derivatives of ammonia) source: wikipedia, accessed: 2019-09-27, Hydrogen nitride source: wikipedia, accessed: 2019-09-27
    • Appearance: Colourless gas source: wikipedia, accessed: 2019-09-27; Colourless gas or compressed liquefied gas with pungent odour source: ICSC, accessed: 2019-09-04; Colorless gas with a pungent, suffocating odor. [Note: Shipped as a liquefied compressed gas. Easily liquefied under pressure.] source: NIOSH NPG, accessed: 2019-09-02
  • SeO2
    • Names: Selenium dioxide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Selenium(IV) oxide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02, Selenous anhydride source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Appearance: White crystals, turn slightly pink with trace decomposition source: wikipedia, accessed: 2019-09-27; Lustrous white hygroscopic crystals or powder. its yellowish green vapour has a pungent sour smell source: ICSC, accessed: 2019-09-04

Products:

  • 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
  • N2
    • Names: Dinitrogen source: wikidata, accessed: 2019-09-07, Nitrogen (compressed gas) source: ICSC, accessed: 2019-09-04, Nitrogen (liquified) source: ICSC, accessed: 2019-09-04
    • Appearance: Odourless colourless compressed gas source: ICSC, accessed: 2019-09-04; Odourless colourless extremely cold liquid source: ICSC, accessed: 2019-09-04
  • Se
    • Names: Selenium source: wikidata, accessed: 2019-09-07source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, Se source: wikidata, accessed: 2019-09-07, Selen source: wikidata, accessed: 2019-09-07
    • Appearance: Grey solid in various forms source: ICSC, accessed: 2019-09-04; Amorphous or crystalline, red to gray solid. [Note: Occurs as an impurity in most sulfide ores.] source: NIOSH NPG, accessed: 2019-09-02