NaOH (aq) + HCN (aq) → H₂O (l) + NaCN (aq)

This is an acid-base reaction (neutralization): NaOH is a base, HCN is an acid.

Reactants:

• NaOH
  • Names: Sodium hydroxide , Caustic soda , Lye ... show moreSoda lye , Sodium hydrate , NaOH , White caustic , Lye [Sodium hydroxide] show less
  • Appearance: White, waxy, opaque crystals ; White hygroscopic solid in various forms ; Colorless to white, odorless solid (flakes, beads, granular form).
• HCN – F , Ormonitrile (substitutive)|Hydridonitridocarbon (additive)}}
  • Other names: Hydrogen cyanide , Ormic anammonide|Hydrocyanic acid|Prussic acid|Methanenitrile , Hydrogen cyanide, liquefied ... show moreHydrocyanic acid , Formonitrile , Prussic acid , [CHN] , HCN show less
  • Appearance: Colorless liquid or gas ; Colourless gas or liquid with characteristic odour ; Colorless or pale-blue liquid or gas (above 78°F) with a bitter, almond-like odor. [Note: Often used as a 96% solution in water.]

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
• 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.