2 NH₄Cl (aq) + K₂Cr₂O₇ (aq) → N₂ (g) + Cr₂O₃ (s) + 2 HCl (aq) + 2 KOH (aq) + 2 H₂O (l)

This is an oxidation-reduction (redox) reaction:

NH₄Cl is a reducing agent, K₂Cr₂O₇ is an oxidizing agent.

This is a precipitation reaction: Cr₂O₃ is the formed precipitate.

This is a gas evolution reaction, N₂ is the formed gas.

Reactants:

• NH₄Cl – Ammonium chloride
  • Other names: Sal ammoniac , Salmiac , Nushadir salt ... show moreSal armagnac , Salt armoniack , Salmiak , Ammonium chloride fume , Amchlor , Ammoneric , Ammonium muriate , Darammon , Sal ammonia , Salammonite , [NH4]Cl , NH4Cl , Ammoniumchlorid , Azanium chloride , Ammonium muriate fume , Sal ammoniac fume show less
  • Appearance: White solid, hygroscopic ; Odourless colourless-to-white hygroscopic solid in various forms ; Finely divided, odorless, white particulate dispersed in air.
• 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

Products:

• N₂
  • Names: Dinitrogen , Nitrogen (compressed gas) , Nitrogen (liquified) ... show moreN₂ , Nitrogen gas , N2 , Nitrogen , Diazyne , Liquid nitrogen , Nitrogen (refrigerated liquid) , Nitrogen (cryogenic liquid) show less
  • Appearance: Odourless colourless compressed gas ; Odourless colourless extremely cold liquid
• Cr₂O₃
  • Names: Chromium(III) oxide , Chromium sesquioxide , Chromia ... show moreChrome green , Eskolaite , Dichromium trioxide , Chromium(iii) oxide , Green oxide of chromium , Green chromium oxide , Chromium(III) sesquioxide , Chromic oxide show less
  • Appearance: Light to dark green, fine crystals ; Light-to-dark-green powder
• 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.]
• KOH – Potassium hydroxide
  • Other names: Caustic potash , Lye , Potash lye ... show morePotassia , Potassium hydrate , KOH , E525 , Potassium lye , Lye [Potassium hydroxide] show less
  • Appearance: White solid, deliquescent ; White hygroscopic solid in various forms ; Odorless, white or slightly yellow lumps, rods, flakes, sticks, or pellets. [Note: May be used as an aqueous solution.]
• 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