2 Cu + 4 KCN + 2 H2O → 2 K[Cu(CN)2] + 2 KOH + H2

This is a complexation reaction: K[Cu(CN)2] is the formed complex.

This is an oxidation-reduction (redox) reaction:

2 Cu0 - 2 e- → 2 CuI (oxidation)

2 HI + 2 e- → 2 H0 (reduction)

Cu is a reducing agent, H2O is an oxidizing agent.

Reactants:

  • Cu
    • Names: Copper source: wikidata, accessed: 2019-09-07source: ICSC, accessed: 2019-09-04, Copper (dusts and mists, as Cu) source: NIOSH NPG, accessed: 2019-09-02, Cu source: wikidata, accessed: 2019-09-07
    • Appearance: Solid in various forms. turns green on exposure to moist air source: ICSC, accessed: 2019-09-04; Reddish, lustrous, malleable, odorless solid. source: NIOSH NPG, accessed: 2019-09-02
  • KCN – Potassium cyanide source: wikipedia, accessed: 2019-09-27source: ICSC, accessed: 2019-09-04
    • Other names: Potassium cyanide (as CN) source: NIOSH NPG, accessed: 2019-09-02, Hydrocyanic acid, potassium salt source: ICSC, accessed: 2019-09-04, Potassium salt of hydrocyanic acid source: NIOSH NPG, accessed: 2019-09-02
    • Appearance: White crystalline solid | deliquescent source: wikipedia, accessed: 2019-09-27; Hygroscopic crystals or solid in various forms with characteristic odour. odourless when dry source: ICSC, accessed: 2019-09-04; White, granular or crystalline solid with a faint, almond-like odor. source: NIOSH NPG, accessed: 2019-09-02
  • 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

Products:

  • K[Cu(CN)2]
  • KOH – Potassium hydroxide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02
    • Other names: Caustic potash source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, Lye source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02, Potash lye source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Appearance: White solid, deliquescent source: wikipedia, accessed: 2019-09-27; White hygroscopic solid in various forms source: ICSC, accessed: 2019-09-04; Odorless, white or slightly yellow lumps, rods, flakes, sticks, or pellets. [Note: May be used as an aqueous solution.] source: NIOSH NPG, accessed: 2019-09-02
  • H2
    • Names: Dihydrogen source: wikidata, accessed: 2019-09-07, Hydrogen source: ICSC, accessed: 2019-09-04source: wikidata, accessed: 2019-09-07, H2 source: wikidata, accessed: 2019-09-07
    • Appearance: Odourless colourless compressed gas source: ICSC, accessed: 2019-09-04