2 BaS + 6 NaHSO₃ → 3 Na₂S₂O₃ + 2 BaSO₃ + 3 H₂O

This is an oxidation-reduction (redox) reaction:

BaS is a reducing agent, NaHSO₃ is an oxidizing agent (synproportionation (comproportionation)).

Reactants:

• BaS
  • Names: Barium sulfide , Bariumsulfid , Barium sulphide ... show more[BaS] , BaS show less
  • Appearance: White solid
• NaHSO₃ – Sodium hydrogen sulfite
  • Other names: Sodium bisulfite , E222 , Sodium bisulphite ... show moreSodium bisulfite 38-40 % aqueous solution , Monosodium salt of sulfurous acid , Sodium acid bisulfite , Bisulfite de sodium , Sodium hydrogensulfite , Natriumbisulfit , Saures Natriumsulfit , Primäres Natriumsulfit , Natriumhydrogensulfit , Sodium acid sulfite , Sodium sulhydrate , Sodium hydrogensulfite aqueous solution , Sodium metabisulfite aqueous solution , Monosodium sulfite , Leucogen , Hydrogen sulfite sodium , Sulfurous acid, monosodium salt show less
  • Appearance: White solid ; Colourless-to-yellow liquid with characteristic odour ; White crystals or powder with a slight odor of sulfur dioxide.

Products:

• Na₂S₂O₃
  • Names: Sodium thiosulfate , Sodium hyposulfite , Hyposulphite of soda ... show moreSodium thiosulfate (anhydrous) , Anhydrous sodium thiosulfate , Sodium thiosulphate , Sodium oxide sulfide , Disodium thiosulfate , Thiosulfuric acid, disodium salt , Sodium thiosulfate anhydrous , Sodium hyposulfit show less
  • Appearance: White crystals ; Colourless crystals
• BaSO₃ – Barium sulfite
  • Appearance: White monoclinic crystals
• 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