K4[Fe(CN)6] + 6H2SO4 + 6H2O → 2K2SO4 + FeSO4 + 3(NH4)2SO4 + 6CO
Potassium hexacyanoferrate(II) react with sulfuric acid and water to produce potassium sulfate, iron(II) sulfate, ammonium sulfate and carbon monoxide. Sulfuric acid - concentrated solution. The reaction takes place in a boiling solution.