8 HCl + K₂Cr₂O₇ + 3 H₂O₂ → 7 H₂O + 3 O₂ + 2 KCl + 2 CrCl₃

This is an oxidation-reduction (redox) reaction:

K₂Cr₂O₇ is an oxidizing agent, H₂O₂ is a reducing agent.

Reactants:

• HCl – Chlorane , Hydrogen chloride
  • Other names: Hydrochloric acid , M , Uriatic acid ... show moreHydronium chloride , Chlorhydric Acid , Hydrochloric acid gas , HCl , Anhydrous hydrogen chloride , Hydrochloric acid, anhydrous , Aqueous hydrogen chloride , [Note: Often used in an aqueous solution.] show less
  • Appearance: Colorless, transparent liquid, fumes in air if concentrated ; Colorless gas ; Colourless compressed liquefied gas with pungent odour ; Colorless to slightly yellow gas with a pungent, irritating odor. [Note: Shipped as a liquefied compressed gas.]
• K₂Cr₂O₇ – Potassium dichromate(VI)
  • Other names: Potassium dichromate , Chromium potassium oxide , Dipotassium dichromium heptaoxide ... show moreDipotassium dichromate , Dipotassium bichromate , Dichromic acid dipotassium salt , Dipotassium dichromate (VI) , Dichromic acid, dipotassium salt , Potassium bichromate show less
  • Appearance: Red-orange crystalline solid ; Orange-to-red crystals
• H₂O₂ – Hydrogen peroxide
  • Other names: Dioxidane , Oxidanyl , Perhydroxic acid ... show more0-hydroxyol , Dihydrogen dioxide , Oxygenated water , Peroxaan , Hydrogen peroxide (>60% solution in water) , H2O2 , Peroxide , Hydroperoxide , Hydrogen dioxide , High-strength hydrogen peroxide , Hydrogen peroxide (aqueous) show less
  • Appearance: Very light blue color; colorless in solution ; Colourless liquid ; Colorless liquid with a slightly sharp odor. [Note: The pure compound is a crystalline solid below 12°F. Often used in an aqueous solution.]

Products:

• H₂O – Water, oxidane
  • Other names: Water (H2O) , Hydrogen hydroxide (HH or HOH) , Hydrogen oxide ... show moreDihydrogen monoxide (DHMO) (systematic name) , Hydrogen monoxide , Dihydrogen oxide , Hydric acid , Hydrohydroxic acid , Hydroxic acid , Hydrol , Μ-oxido dihydrogen , Κ1-hydroxyl hydrogen(0) show less
  • Appearance: White crystalline solid, almost colorless liquid with a hint of blue, colorless gas
• O₂
  • Names: Dioxygen , Oxygen , Oxygen (liquefied) ... show moreO2 , O₂ , Oxygen gas , Molecular oxygen , Oxygen, refrigerated liquid , LOX , Liquid oxygen show less
  • Appearance: Odourless compressed gas ; Liquefied gas. colourless-to-blue extremely cold liquid
• KCl
  • Names: Potassium chloride , Sylvite , Muriate of potash ... show moreKlor-Con M15 , K-Lease , Klor-Con 8 , K+10 , K+8 , Klor-Con M10 , Micro-K 10 , Kato , Kaon Cl-10 , Kaon-Cl , Kaon Cl , Micro-K , Klor-Con 10Meq , Klor-Con 10 , Micro-K Ls , K-dur , Klor-Con , Klor-Con M20 , Slow-K , Ten-K , Klotrix , [KCl] , Kaliumchlorid , Chloride of potash , Kaon-CL 10 , Klor-CON , KCl , Monopotassium chloride , K-Tab , Chlorid draselny , Potassium Chloride show less
  • Appearance: White crystalline solid ; Colourless hygroscopic crystals
• CrCl₃ – Chromium(III) chloride , Chromium trichloride
  • Other names: Chromic chloride , Chromium(iii) chloride (anhydrous) , Chromium(3+) trichloride ... show moreCrCl3 , Anhydrous chromium(III) chloride , Chromium chloride , Puratronic chromium chloride , Trichlorochromium , Chromic chloride anhydrous show less
  • Appearance: Purple (anhydrous), dark green (hexahydrate) ; Violet crystals