Moist, acidic environments promote the corrosion of iron metal when dissolved…
CHEMISTRY · Multi-part · A Level · Chemistry · Oxidation, reduction and redox reactions · Oxidation, reduction and redox reactions
Problem
Moist, acidic environments promote the corrosion of iron metal when dissolved molecular oxygen is present. Assume the following half-reactions accurately represent the chemistry occurring at the metal surface and in the surrounding solution.
Anodic half-reaction: Fe→Fe2++2e−
Cathodic half-reaction: O2+4H++4e−→2H2O
(a) Combine the two half-reactions to write the overall balanced ionic equation for the corrosion process in acidic solution.
(b) When coefficients are reduced to the smallest whole numbers, what is the stoichiometric coefficient in front of O2 in the balanced equation from part (a)?
(c) Determine the number of moles of electrons transferred per mole of Fe consumed according to the balanced equation.
(d) Briefly explain, in terms of redox potentials and the half-reactions provided, why lowering the pH of the environment accelerates the corrosion of iron.