3 SO2 + K2Cr2O7 + H2SO4 2 KCr(SO4)2 + H2O

This is an oxidation-reduction (redox) reaction:

3 SIV - 6 e- 3 SVI (oxidation)

2 CrVI + 6 e- 2 CrIII (reduction)

SO2 is a reducing agent, K2Cr2O7 is an oxidizing agent.

Reactants:

  • SO2Sulfur 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
  • K2Cr2O7Potassium 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
  • H2SO4Sulfuric acid source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-07source: NIOSH NPG, accessed: 2019-09-02
    • Other names: Oil of vitriol source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-07source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, Sulfuric acid, concentrated (> 51% and < 100%) source: ICSC, accessed: 2019-09-04, H2SO4 source: wikidata, accessed: 2019-09-07
    • Appearance: Clear, colorless liquid source: wikipedia, accessed: 2019-09-27; Odourless colourless oily hygroscopic liquid source: ICSC, accessed: 2019-09-04; Colorless to dark-brown, oily, odorless liquid. [Note: Pure compound is a solid below 51°F. Often used in an aqueous solution.] source: NIOSH NPG, accessed: 2019-09-02

Products:

  • KCr(SO4)2Chromium potassium sulfate source: wikipedia, accessed: 2019-09-27
    • Other names: Potassium chromium sulfate source: wikipedia, accessed: 2019-09-27, Chromium alum source: wikipedia, accessed: 2019-09-27, Chrome alum source: wikidata, accessed: 2019-09-02
    • Appearance: Dark purple needles or greyish-brown powder when anhydrous source: wikipedia, accessed: 2019-09-27
  • H2OWater, 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