Cl2 (g) + 4 Na2S2O3 (aq) → 2 NaCl (aq) + 5 S (s) + 3 Na2SO4 (aq)

This is an oxidation-reduction (redox) reaction:

5 SII + 10 e- → 5 S0 (reduction)

3 SII - 12 e- → 3 SVI (oxidation)

2 Cl0 + 2 e- → 2 Cl-I (reduction)

Na2S2O3 is an oxidizing agent, Na2S2O3 is a reducing agent, Cl2 is an oxidizing agent.

Reactants:

  • Cl2
    • Names: Chlorine source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, Molecular chlorine source: NIOSH NPG, accessed: 2019-09-02
    • Appearance: Greenish-yellow compressed liquefied gas with pungent odour source: ICSC, accessed: 2019-09-04; Greenish-yellow gas with a pungent, irritating odor. [Note: Shipped as a liquefied compressed gas.] source: NIOSH NPG, accessed: 2019-09-02
  • Na2S2O3
    • Names: Sodium thiosulfate source: wikipedia, accessed: 2019-09-28source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Sodium hyposulfite source: wikipedia, accessed: 2019-09-28source: wikidata, accessed: 2019-09-02, Hyposulphite of soda source: wikipedia, accessed: 2019-09-28
    • Appearance: White crystals source: wikipedia, accessed: 2019-09-28; Colourless crystals source: ICSC, accessed: 2019-09-04

Products:

  • NaCl – Sodium chloride source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Other names: {{unbulleted list source: wikipedia, accessed: 2019-09-27, Salt source: wikidata, accessed: 2019-09-02, Table salt source: wikidata, accessed: 2019-09-02
    • Appearance: Colorless cubic crystals source: wikipedia, accessed: 2019-09-27
  • 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
  • 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