K4[Fe(CN)6] + KNO2 + 2CH3COOH → K3[Fe(CN)6] + CH3COOK + NO + H2O
Potassium hexacyanoferrate(II) react with potassium nitrite and acetic acid to produce potassium hexacyanoferrate(III), potassium acetate, nitric oxide and water. Acetic acid - diluted solution.