4 As + 5 O2 2 As2O5

This is an oxidation-reduction (redox) reaction:

4 As0 - 20 e- 4 AsV (oxidation)

10 O0 + 20 e- 10 O-II (reduction)

As is a reducing agent, O2 is an oxidizing agent.

Reactants:

  • As
    • Names: Arsenic source: ICSC, accessed: 2019-09-04, Grey arsenic source: ICSC, accessed: 2019-09-04
    • Appearance: Brittle grey metallic-looking crystals source: ICSC, accessed: 2019-09-04
  • O2
    • Names: Dioxygen source: wikidata, accessed: 2019-09-07, Oxygen source: ICSC, accessed: 2019-09-04source: wikidata, accessed: 2019-09-07, Oxygen (liquefied) source: ICSC, accessed: 2019-09-04
    • Appearance: Odourless compressed gas source: ICSC, accessed: 2019-09-04; Liquefied gas. colourless-to-blue extremely cold liquid source: ICSC, accessed: 2019-09-04

Products:

  • As2O5
    • Names: Diarsenic pentoxide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Arsenic(V) oxide source: wikipedia, accessed: 2019-09-27, Arsenic oxide source: wikipedia, accessed: 2019-09-27
    • Appearance: White hygroscopic powder source: wikipedia, accessed: 2019-09-27; White hygroscopic powder source: ICSC, accessed: 2019-09-04