NaClO₂ (aq) + 4 HCl (aq) → NaCl (aq) + 2 Cl₂ (g) + 2 H₂O (l)

This is an oxidation-reduction (redox) reaction:

HCl is a reducing agent, NaClO₂ is an oxidizing agent (synproportionation (comproportionation)).

This is a gas evolution reaction, Cl₂ is the formed gas.

Reactants:

• NaClO₂ – Sodium chlorite
  • Other names: Chlorous acid , Sodium salt , Textone ... show moreNaO2Cl , NaClO2 , Chlorous acid, sodium salt , Chlorite sodium show less
  • Appearance: White solid ; Slightly hygroscopic white crystals or flakes
• 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.]

Products:

• NaCl – Sodium chloride
  • Other names: {{unbulleted list , Salt , Table salt ... show moreCommon salt , NaCl , Broncho saline show less
  • Appearance: Colorless cubic crystals
• Cl₂
  • Names: Chlorine , Molecular chlorine
  • Appearance: Greenish-yellow compressed liquefied gas with pungent odour ; Greenish-yellow gas with a pungent, irritating odor. [Note: Shipped as a liquefied compressed gas.]
• 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