NaHSO₃ + 2 NaCN + 2 CuSO₄ + H₂O → 2 CuCN + 3 NaHSO₄

This is an oxidation-reduction (redox) reaction:

NaHSO₃ is a reducing agent, NaCN is an oxidizing agent.

Reactants:

• 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.
• NaCN
  • Names: Sodium cyanide , Sodium cyanide (as CN) , Sodium salt of hydrocyanic acid , Hydrocyanic acid, sodium salt
  • Appearance: White solid ; White hygroscopic crystalline powder with characteristic odour. odourless when dry ; White, granular or crystalline solid with a faint, almond-like odor.
• CuSO₄ – Copper(II) sulfate
  • Other names: Cupric sulphate , Blue vitriol (pentahydrate) , Bluestone (pentahydrate) ... show moreBonattite (trihydrate mineral) , Boothite (heptahydrate mineral) , Chalcanthite (pentahydrate mineral) , Chalcocyanite (mineral) , Cupric sulfate , Copper sulfate (anhydrous) , CuSO4 , Copper sulfate , Cupric sulfate anhydrous , Copper monosulphate , Copper sulfate (1:1) , Cupric sulphate anhydrous , Copper sulphate , Copper(2+) sulfate , Copper(II) sulphate , Copper monosulfate , Cupric sulfate, anhydrous , Cupric sulphate, anhydrous , Sulfuric acid, copper(2+) salt(1:1) show less
  • Appearance: Gray-white (anhydrous) | blue (pentahydrate) ; White hygroscopic 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

Products:

• CuCN – Copper(I) cyanide
  • Other names: Cuprous cyanide , Copper cyanide , Cupricin
  • Appearance: Off-white / pale yellow powder
• NaHSO₄ – Sodium hydrogen sulfate
  • Other names: Sodium bisulfate , Sodium acid sulfate , Bisulfate of soda
  • Appearance: White solid