Explain the passivation behavior of iron in nitric acid Refe

Explain the passivation behavior of iron in nitric acid. Refer to your observations from Experiment 5 What do you think would happen to the passivated sample of iron if left in dilute nitric acid for a long time? Explain.

Solution

It is probable that iron immersed in dilute nitric acid should become passive, since nitric acid is oxidizing in nature, and that it will form a protective film on iron.

Fe + 2HNO₃ = Fe(NO₃)₂ + H₂   = FeO + NO₂ + H₂O

FeO + H₂O = Fe(OH)₂