5K4[Fe(CN)6] + 8HCl + KMnO4 → 5K3[Fe(CN)6] + MnCl2 + 6KCl + 4H2O
Potassium hexacyanoferrate(II) react with hydrogen chloride and potassium permanganate to produce potassium hexacyanoferrate(III), manganese(II) chloride, potassium chloride and water. Hydrogen chloride - diluted solution.