Corrosion Cell Reactions and Acids

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Questions and Answers

What is the anodic reaction in a corrosion cell?

M → M + z + ze (correct)
O 2 + 4 H + + 4 e - → 2 H 2 O
2 H + + 2 e - → H 2
M + z + ze → M

Which of the following cathodic reactions occurs in O2 rich acidic media?

O 2 + 4 H + + 4 e - → 2 H 2 O (correct)
2 H + + 2 e - → H 2
2 H 2 O + 2 e - → H 2 + 2 OH -
O 2 + 2 H 2 O + 4 e - → 4 OH -

What type of media produces the cathodic reaction 2 H2O + 2 e - → H2 + 2 OH -?

O2 poor acidic media
O2 rich acidic media
O2 poor non acidic media (correct)
O2 rich non acidic media

Which of the following statements regarding acids is correct?

<p>Very strong acids, like H2SO4, can be very corrosive. (D)</p> Signup and view all the answers

Which of the following options correctly compares strong bases to weak bases in terms of corrosiveness?

<p>Strong bases are more corrosive than weak bases. (D)</p> Signup and view all the answers

Flashcards

Anodic Reaction

The process where a metal atom loses electrons and forms a positive ion (cation). This is the first step in corrosion.

Cathodic Reaction (O2 rich, acidic)

This reaction involves oxygen and hydrogen ions (H+) in acidic environments. It's the most common reaction where electrons are gained.

Cathodic Reaction (O2 rich, non-acidic)

This reaction involves oxygen and water in non-acidic environments. It's common where oxygen is available and the environment is not acidic.

Cathodic Reaction (O2 poor, acidic)

This reaction involves hydrogen ions (H+) in environments with limited oxygen. It's less common than the oxygen-based reactions.

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Cathodic Reaction (O2 poor, non-acidic)

This reaction involves water in environments with limited oxygen and is not acidic. It's the least common corrosion reaction.

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Study Notes

Corrosion Cell Reactions

Anodic reaction: M → M^+z + ze^- (Metal loses electrons)
Cathodic reactions vary depending on the environment:
- Oxygen-rich acidic media: O₂ + 4H⁺ + 4e^- → 2H₂O, E^o = 1.23 V
- Oxygen-rich non-acidic media: O₂ + 2H₂O + 4e^- → 4OH^-, E^o = 0.401 V
- Oxygen-poor acidic media: 2H⁺ + 2e^- → H₂, E^o = 0.0 V
- Oxygen-poor non-acidic media: 2H₂O + 2e^- → H₂ + 2OH^-, E^o = -0.828 V

Acids

Acids are corrosive environments.
Strength of acids varies:
- Very weak: Fatty acids, organic acids
- Weak: Acetic acid, formic acid
- Strong: Sulfuric acid (H₂SO₄), Nitric acid (HNO₃), Phosphoric acid (H₃PO₄), Hydrochloric acid (HCl)

Bases

Strong bases (like sodium hydroxide, potassium hydroxide) are more corrosive than weak bases (like ammonia solution).

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Description

Explore the intricacies of corrosion cell reactions, including anodic and cathodic processes in various environments. Learn about the role of acids in corrosion and the varying strengths of different types of acids. This quiz will test your knowledge on chemical reactions related to corrosion.