COMEDK2024Evening ShiftChemistryElectrochemistryActual
Identify the correct statement regarding corrosion of iron rod left exposed to atmosphere.
Options
- AThe reaction occurring at the cathodic area is: O ₂( ~g )+2 H ₂ O ( l )+4 e 4 OH ⁻
- BThe overall reaction occurring during the corrosion process is: 2 Fe _ ( S ) +3 / 2 O ₂( ~g )+6 H ⁺ 2 Fe ³⁺+3
- CThe reaction occurring at the cathodic area is: O ₂( ~g )+4 H ⁺( aq )+4 e 2 H ₂ O ( l ) ; E ^0=+1.23 ~V
- DReaction occurring at anodic area is: 2 H ₂ O ( l ) O ₂( ~g )+4 H ⁺+4 e
Correct answer
C. The reaction occurring at the cathodic area is: O ₂( ~g )+4 H ⁺( aq )+4 e 2 H ₂ O ( l ) ; E ^0=+1.23 ~V
Step-by-step solution
At the anodic area: 2Fe(s) 2Fe²⁺(aq) + 4e^- (oxidation) At the cathodic area: O₂(g) + 4H^+(aq) + 4e^- 2H₂O(l) ; E° = +1.23 V H^+ ions come from dissolution of atmospheric CO₂ in moisture forming weak carbonic acid. Option (3) correctly states the cathodic reaction with E° = +1.23 V.