What happens during corrosion of a metal? State the electrochemical basis of corrosion of iron.

Solution

Answer:

Corrosion slowly coats the surfaces of metallic objects with oxides or other salts of the metal.

Metal reacts with gases present in atmosphere to form surface compounds in corrosion. The electrochemical basis of corrosion of iron is as follows:

Iron in contact with the dissolved CO₂ and O₂undergoes oxidation as follows:
Fe → Fe²⁺ + 2e^– E°_oxidation = + 0.44 V

The elctrons lost by iron are taken up by the H⁺ ions present on the surface of the metal which were produced by the dissociation of H₂CO₃ and H₂O.

H^{+} + e^{-} \to H 4 H + O_{2} \to 2 H_{2} O O_{2} + 4 H^{+} + 4 e^{-} \to 2 H_{2} O [{E^{0}}_{red} = 1.23 V] O_{2} + 2 H_{2} O + 4 e^{-} \to 4 OH 2 Fe + O_{2} + 4 H^{+} \to 2 {Fe}^{2 +} (aq) + 2 H_{2} O (l) [{E^{0}}_{cell} = 1.67 V]

Some More Questions From Electrochemistry Chapter

Why does the conductivity of a solution decrease with dilution?

Suggest a way to determine the Λ°_m value of water.

The molar conductivity of 0.025 mol L^–1methanoic acid is 46.1 S cm² mol^–1. Calculate its degree of dissociation and dissociation constant. Give λ°(H⁺) = 349.6 S cm²mol^–1 and λ° (HCOO^– ) = 54.6 s cm² mol^–1.

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Electrochemistry

What happens during corrosion of a metal? State the electrochemical basis of corrosion of iron.

Some More Questions From Electrochemistry Chapter

Why does the conductivity of a solution decrease with dilution?

Suggest a way to determine the Λ°_m value of water.

The molar conductivity of 0.025 mol L^–1methanoic acid is 46.1 S cm² mol^–1. Calculate its degree of dissociation and dissociation constant. Give λ°(H⁺) = 349.6 S cm²mol^–1 and λ° (HCOO^– ) = 54.6 s cm² mol^–1.

If the current of 0.5 ampere flows through a metallic wire for 2 hours, then how many electrons flow through the wire?

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What is the quantity of electricity in coulombs needed to reduce 1 mol of Cr₂O₇^2-?

Write the chemistry of recharging the lead storage battery, highlighting all the materials that are involved during recharging.

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For Daily Free Study Material Join wiredfaculty

Electrochemistry

What happens during corrosion of a metal? State the electrochemical basis of corrosion of iron.

Some More Questions From Electrochemistry Chapter

Why does the conductivity of a solution decrease with dilution?

Suggest a way to determine the Λ°m value of water.

The molar conductivity of 0.025 mol L–1 methanoic acid is 46.1 S cm2 mol–1. Calculate its degree of dissociation and dissociation constant. Give λ°(H+) = 349.6 S cm2 mol–1 and λ° (HCOO– ) = 54.6 s cm2 mol–1.

If the current of 0.5 ampere flows through a metallic wire for 2 hours, then how many electrons flow through the wire?

Suggest a list of metals that are extracted electrolytically.

Consider the reaction: Cr2O72– + 14H+ + 6e- → 2Cr3+ + 8H2OWhat is the quantity of electricity in coulombs needed to reduce 1 mol of Cr2O72-?

Write the chemistry of recharging the lead storage battery, highlighting all the materials that are involved during recharging.

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

Suggest a way to determine the Λ°_m value of water.

The molar conductivity of 0.025 mol L^–1methanoic acid is 46.1 S cm² mol^–1. Calculate its degree of dissociation and dissociation constant. Give λ°(H⁺) = 349.6 S cm²mol^–1 and λ° (HCOO^– ) = 54.6 s cm² mol^–1.

Consider the reaction: Cr₂O₇^2– + 14H⁺ + 6e- → 2Cr³⁺ + 8H₂O
What is the quantity of electricity in coulombs needed to reduce 1 mol of Cr₂O₇^2-?