3 NaNO3 (aq) + Cr2O3 (s) + 4 KOH (aq) → 3 NaNO2 (aq) + 2 K2CrO4 (aq) + 2 H2O (l)

This is an oxidation-reduction (redox) reaction:

3 NV + 6 e- → 3 NIII (reduction)

2 CrIII - 6 e- → 2 CrVI (oxidation)

NaNO3 is an oxidizing agent, Cr2O3 is a reducing agent.

Reactants:

  • NaNO3 – Sodium nitrate source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04
    • Other names: Peru saltpeter source: wikipedia, accessed: 2019-09-27, Soda niter source: wikipedia, accessed: 2019-09-27, Cubic niter source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Appearance: White powder or colorless crystals source: wikipedia, accessed: 2019-09-27; Colourless hygroscopic crystals 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
  • KOH – Potassium hydroxide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02
    • Other names: Caustic potash source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, Lye source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02, Potash lye source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Appearance: White solid, deliquescent source: wikipedia, accessed: 2019-09-27; White hygroscopic solid in various forms source: ICSC, accessed: 2019-09-04; Odorless, white or slightly yellow lumps, rods, flakes, sticks, or pellets. [Note: May be used as an aqueous solution.] source: NIOSH NPG, accessed: 2019-09-02

Products:

  • NaNO2
    • Names: Sodium nitrite source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, 7632-00-0 source: wikidata, accessed: 2019-09-02, E250 source: wikidata, accessed: 2019-09-02
    • Appearance: White or slightly yellowish solid source: wikipedia, accessed: 2019-09-27; Hygroscopic white-to-yellow solid in various forms source: ICSC, accessed: 2019-09-04
  • K2CrO4 – Potassium chromate source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04
    • Other names: Chromic acid source: wikipedia, accessed: 2019-09-27, (K2CrO4) source: wikipedia, accessed: 2019-09-27, Dipotassium salt source: wikipedia, accessed: 2019-09-27
    • Appearance: Yellow powder source: wikipedia, accessed: 2019-09-27; Yellow crystals source: ICSC, accessed: 2019-09-04
  • H2O – Water, 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