2 HNO₃ (aq) + Na₂SO₃ (aq) → H₂O (l) + Na₂SO₄ (aq) + 2 NO₂ (l)

This is an acid-base reaction (neutralization): HNO₃ is an acid, Na₂SO₃ is a base.

This is an oxidation-reduction (redox) reaction:

Na₂SO₃ is a reducing agent, HNO₃ is an oxidizing agent.

Reactants:

• HNO₃ – Nitric acid
  • Other names: Aqua fortis , Spirit of niter , Eau forte ... show moreHydrogen nitrate , Acidum nitricum , Nitric acid (> 70% in water) , Fuming nitric acid , Engravers acid , HONO2 , Red fuming nitric acid , RFNA , White fuming nitric acid (WFNA) show less
  • Appearance: Colorless, yellow or red fuming liquid ; Colourless-to-yellow liquid with pungent odour ; Colorless, yellow, or red, fuming liquid with an acrid, suffocating odor. [Note: Often used in an aqueous solution. Fuming nitric acid is concentrated nitric acid that contains dissolved nitrogen dioxide.]
• Na₂SO₃ – Sodium sulfite
  • Other names: Sodium sulphite , Hypo clear (photography) , E221 ... show moreNa2SO3 , Anhydrous sodium sulfite , Sodium sulfite anhydrous , Sulfurous acid, disodium salt , Dried sodium sulfite , Disodium sulfite show less
  • Appearance: White solid ; White crystals or powder

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
• Na₂SO₄
  • Names: Sodium sulfate , Sodium sulphate , Sulfate of sodium ... show moreThenardite (mineral) , Glauber's salt (decahydrate) , Sal mirabilis (decahydrate) , Mirabilite (decahydrate mineral) , Disodium sulfate , Anhydrous sodium sulfate , Sodium sulfate anhydrous , Sodium sulfate, anhydrous , Sodium sulphate anhydrous , Sodium sulphate, anhydrous , Sulfuric acid disodium salt, anhydrous , Disodium sulphate , Salt cake , Na2SO4 , Sulfuric acid disodium salt show less
  • Appearance: White crystalline solid | hygroscopic ; White hygroscopic solid in various forms
• NO₂ – Nitrogen dioxide
  • Other names: Nitrogen(IV) oxide , Deutoxide of nitrogen , Nitrogen peroxide ... show moreNO2 , NO2(.) , Dinitrogen tetroxide (see notes) , Nitrogen tetroxide , Dinitrogen tetroxide show less
  • Appearance: Brown gas ; Reddish-brown gas or brown or yellow liquid with pungent odour ; Yellowish-brown liquid or reddish-brown gas (above 70°F) with a pungent, acrid odor. [Note: In solid form (below 15°F) it is found structurally as N2O4.]