Na2Cr2O7 (aq) + S (s) → Na2SO4 (aq) + Cr2O3 (s)

This is an oxidation-reduction (redox) reaction:

S0 - 6 e- → SVI (oxidation)

2 CrVI + 6 e- → 2 CrIII (reduction)

S is a reducing agent, Na2Cr2O7 is an oxidizing agent.

Reactants:

  • Na2Cr2O7 – Sodium dichromate source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Other names: Chromic acid disodium salt source: wikipedia, accessed: 2019-09-27, Sodium dichromate (anhydrous) source: ICSC, accessed: 2019-09-04, Disodium salt source: wikidata, accessed: 2019-09-02
    • Appearance: Bright orange source: wikipedia, accessed: 2019-09-27; Red-to-orange hygroscopic crystals source: ICSC, accessed: 2019-09-04
  • S
    • 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:

  • Na2SO4
    • Names: Sodium sulfate source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Sodium sulphate source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02, Sulfate of sodium source: wikipedia, accessed: 2019-09-27
    • Appearance: White crystalline solid | hygroscopic source: wikipedia, accessed: 2019-09-27; White hygroscopic solid in various forms source: ICSC, accessed: 2019-09-04
  • 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