K3[Fe(CN)6] + 3HCl → H3[Fe(CN)6] + 3KCl
Potassium hexacyanoferrate(III) react with hydrogen chloride to produce hexacyanoferrate hydrogen and potassium chloride. Potassium hexacyanoferrate(III) - saturated solution. Hydrogen chloride - concentrated solution. This reaction takes place at a temperature near 0°C.