Redox Reactions And Electrochemistry Ques 83
Question: Corrosion of iron is essentially an electrochemical phenomenon where the cell reactions are [KCET 2005]
Options:
A) $ Fe $ is oxidised to $ F{e^{2+}} $ and dissolved oxygen in water is reduced to $ \overset{,}{\mathop{OH}}, $
B) $ Fe $ is oxidised to $ F{e^{3+}} $ and $ H_2O $ is reduced to $ O_2^{2-} $
C) $ Fe $ is oxidised to $ F{e^{2+}} $ and $ H_2O $ is reduced to $ O_2^{-} $
D) $ Fe $ is oxidised to $ F{e^{2+}} $ and $ H_2O $ is reduced to $ O_2 $
Show Answer
Answer:
Correct Answer: A
Solution:
$ Fe\to F{e^{2+}}+2e $ (anode reaction) $ O_2+2H_2O+4e\to 4O{H^{-}} $ (cathode reaction)
The overall reaction is $ 2Fe+O_2+2H_2O\to 2Fe{{(OH)}_2} $ $ Fe{{(OH)}_2} $ may be dehydrated to iron oxide $ FeO $ , or further oxidised to $ Fe{{(OH)}_3} $ and then dehydrated to iron rust, $ Fe_2O_3 $ .
