8 HClO4 + K2Cr2O7 + 6 HI 2 Cr(ClO4)3 + 2 KClO4 + 3 I2 + 7 H2O

This is an oxidation-reduction (redox) reaction:

6 I-I - 6 e- 6 I0 (oxidation)

2 CrVI + 6 e- 2 CrIII (reduction)

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

Reactants:

  • HClO4Chloric(VII) acid source: wikipedia, accessed: 2019-09-27
    • Other names: Perchloric acid source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02, Hyperchloric acid source: wikipedia, accessed: 2019-09-27, Perchloric acid (72% solution) source: ICSC, accessed: 2019-09-04, Hydronium perchlorate source: ICSC, accessed: 2019-09-04
    • Appearance: Colorless liquid source: wikipedia, accessed: 2019-09-27; Colourless liquid with pungent odour source: ICSC, accessed: 2019-09-04
  • 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
  • HIIodane source: wikipedia, accessed: 2019-09-27
    • Other names: Hydroiodic acid source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02, Hydrogen iodide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Hydronium iodide source: wikipedia, accessed: 2019-09-27
    • Appearance: Colorless liquid source: wikipedia, accessed: 2019-09-27; Colorless gas source: wikipedia, accessed: 2019-09-27; Colourless compressed liquefied gas with pungent odour source: ICSC, accessed: 2019-09-04

Products:

  • Cr(ClO4)3
    • KClO4
      • Names: Potassium perchlorate source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Potassium chlorate(VII); Perchloric acid source: wikipedia, accessed: 2019-09-27, Potassium salt; peroidin source: wikipedia, accessed: 2019-09-27
      • Appearance: Colourless/ white crystalline powder source: wikipedia, accessed: 2019-09-27; Colourless crystals or white crystalline powder source: ICSC, accessed: 2019-09-04
    • I2
      • Names: Iodine source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, Jod source: ICSC, accessed: 2019-09-04, Iode source: ICSC, accessed: 2019-09-04
      • Appearance: Bluish black or dark purple crystals with pungent odour source: ICSC, accessed: 2019-09-04; Violet solid with a sharp, characteristic odor. source: NIOSH NPG, accessed: 2019-09-02
    • 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