16 K2Cr2O7 + 3 S8 → 24 SO2 + 16 Cr2O3 + 16 K2O

This is an oxidation-reduction (redox) reaction:

24 S0 - 96 e- → 24 SIV (oxidation)

32 CrVI + 96 e- → 32 CrIII (reduction)

S8 is a reducing agent, K2Cr2O7 is an oxidizing agent.

Reactants:

  • K2Cr2O7 – Potassium dichromate(VI) source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Other names: Potassium dichromate source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Chromium potassium oxide source: wikidata, accessed: 2019-09-02, Dipotassium dichromium heptaoxide source: wikidata, accessed: 2019-09-02
    • Appearance: Red-orange crystalline solid source: wikipedia, accessed: 2019-09-27; Orange-to-red crystals source: ICSC, accessed: 2019-09-04
  • S8
    • Names: Sulfur source: wikidata, accessed: 2019-09-07source: ICSC, accessed: 2019-09-04, S source: wikidata, accessed: 2019-09-07, Sulphur source: wikidata, accessed: 2019-09-07source: ICSC, accessed: 2019-09-04
    • Appearance: Yellow solid in various forms source: ICSC, accessed: 2019-09-04

Products:

  • 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
  • Cr2O3
    • Names: Chromium(III) oxide source: wikipedia, accessed: 2019-09-27, Chromium sesquioxide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02, Chromia source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Appearance: Light to dark green, fine crystals source: wikipedia, accessed: 2019-09-27; Light-to-dark-green powder source: ICSC, accessed: 2019-09-04
  • K2O – Potassium oxide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Potassium oxidopotassium source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Other names: Potash source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02, Dipotassium oxide source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Dipotassium monoxide source: wikidata, accessed: 2019-09-02
    • Appearance: Pale yellow solid source: wikipedia, accessed: 2019-09-27; Grey hygroscopic crystalline powder source: ICSC, accessed: 2019-09-04