2 KCN (aq) + 2 H₂SO₄ (aq) + 2 H₂O (l) → K₂SO₄ (aq) + (NH₄)₂SO₄ (aq) + 2 CO (g)

This is an acid-base reaction (neutralization): KCN is a base, H₂SO₄ is an acid.

Reactants:

KCN – Potassium cyanide
- Other names: Potassium cyanide (as CN) , Hydrocyanic acid, potassium salt , Potassium salt of hydrocyanic acid
- Appearance: White crystalline solid | deliquescent ; Hygroscopic crystals or solid in various forms with characteristic odour. odourless when dry ; White, granular or crystalline solid with a faint, almond-like odor.
H₂SO₄ – Sulfuric acid
- Other names: Oil of vitriol , Sulfuric acid, concentrated (> 51% and < 100%) , H2SO4
- Appearance: Clear, colorless liquid ; Odourless colourless oily hygroscopic liquid ; Colorless to dark-brown, oily, odorless liquid. [Note: Pure compound is a solid below 51°F. Often used in an aqueous solution.]
H₂O – Water, oxidane
- Other names: Water (H2O) , Hydrogen hydroxide (HH or HOH) , Hydrogen oxide
- Appearance: White crystalline solid, almost colorless liquid with a hint of blue, colorless gas

Products:

K₂SO₄
- Names: Potassium sulfate , Potassium sulphate , Dipotassium sulfate
- Appearance: White solid ; Colourless-to-white crystals
(NH₄)₂SO₄ – Ammonium tetraoxosulfate (VI)
- Other names: Ammonium sulphate , Ammonium sulfate , Ammonium sulfate (2:1)
- Appearance: Fine white hygroscopic granules or crystals.
CO – Carbon monoxide
- Other names: Carbon monooxide , Carbonous oxide , Carbon(II) oxide
- Appearance: Colorless gas ; Odourless tasteless colourless compressed gas ; Colorless, odorless gas. [Note: Shipped as a nonliquefied or liquefied compressed gas.]

2 KCN (aq) + 2 H2SO4 (aq) + 2 H2O (l) → K2SO4 (aq) + (NH4)2SO4 (aq) + 2 CO (g)