3Na3[Co(NO2)6] + 2HNO3 → 9NaNO2 + 3Co(NO3)2 + 5NO + H2O
Sodium hexanitrocobaltate(III) react with nitric acid to produce sodium nitrite, nitrate cobalt(II), nitric oxide and water. Nitric acid - diluted solution. The reaction takes place in a boiling solution.