5 NaClO2 (aq) + 4 HCl (aq) → 4 ClO2 (g) + 5 NaCl (aq) + 2 H2O (l)

This is an oxidation-reduction (redox) reaction:

ClIII + 4 e- → Cl-I (reduction)

4 ClIII - 4 e- → 4 ClIV (oxidation)

NaClO2 is both an oxidizing and a reducing agent (disproportionation (dismutation)).

This is a gas evolution reaction, ClO2 is the formed gas.

Reactants:

  • NaClO2 – Sodium chlorite source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04
    • Other names: Chlorous acid source: wikipedia, accessed: 2019-09-27, Sodium salt source: wikipedia, accessed: 2019-09-27, Textone source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Appearance: White solid source: wikipedia, accessed: 2019-09-27; Slightly hygroscopic white crystals or flakes source: ICSC, accessed: 2019-09-04
  • HCl – Chlorane source: wikipedia, accessed: 2019-09-27, Hydrogen chloride source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02
    • Other names: Hydrochloric acid source: wikipedia, accessed: 2019-09-27source: NIOSH NPG, accessed: 2019-09-02, M source: wikipedia, accessed: 2019-09-27, Uriatic acid source: wikipedia, accessed: 2019-09-27
    • Appearance: Colorless, transparent liquid, fumes in air if concentrated 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; Colorless to slightly yellow gas with a pungent, irritating odor. [Note: Shipped as a liquefied compressed gas.] source: NIOSH NPG, accessed: 2019-09-02

Products:

  • ClO2 – Chlorine dioxide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, 4-chlorane (substitutive) OR Dioxidochlorine(•) (additive) --> source: wikipedia, accessed: 2019-09-27
    • Other names: Chlorine(IV) oxide source: wikipedia, accessed: 2019-09-27, Chlorine oxide source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, Chlorine peroxide source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02
    • Appearance: Yellow to reddish gas source: wikipedia, accessed: 2019-09-27; Red-yellow gas with pungent odour source: ICSC, accessed: 2019-09-04; Yellow to red gas or a red-brown liquid (below 52°F) with an unpleasant odor similar to chlorine and nitric acid. source: NIOSH NPG, accessed: 2019-09-02
  • NaCl – Sodium chloride source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Other names: {{unbulleted list source: wikipedia, accessed: 2019-09-27, Salt source: wikidata, accessed: 2019-09-02, Table salt source: wikidata, accessed: 2019-09-02
    • Appearance: Colorless cubic crystals source: wikipedia, accessed: 2019-09-27
  • 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