(a) Write the anode and cathode reactions that cause the corrosion of iron metal to aqueous iron(II).

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Identify the overall process of iron corrosion, which involves the oxidation of iron metal to iron(II) ions and the reduction of oxygen in the presence of water.

Write the anode reaction, where iron metal (Fe) is oxidized to iron(II) ions (Fe^{2+}). The reaction is: Fe(s) \rightarrow Fe^{2+}(aq) + 2e^{-}.

Write the cathode reaction, which involves the reduction of oxygen in the presence of water. The reaction is: O_2(g) + 4H^+(aq) + 4e^{-} \rightarrow 2H_2O(l).

Combine the anode and cathode reactions to understand the overall redox process occurring during the corrosion of iron.

Consider the environmental conditions, such as the presence of water and oxygen, which facilitate the corrosion process.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Corrosion

Corrosion is the electrochemical process where metals, such as iron, react with environmental elements like oxygen and moisture, leading to deterioration. In the case of iron, corrosion typically results in the formation of iron oxides, commonly known as rust. Understanding the conditions that promote corrosion is essential for preventing it and protecting metal structures.

Electrochemical Reactions

Electrochemical reactions involve the transfer of electrons between chemical species, which can occur in galvanic cells. In the context of iron corrosion, the anode reaction involves the oxidation of iron to iron(II) ions, while the cathode reaction typically involves the reduction of oxygen. These reactions are crucial for understanding how metals corrode and the overall process of electrochemical degradation.

Anode and Cathode Reactions

In electrochemistry, the anode is the electrode where oxidation occurs, and the cathode is where reduction takes place. For iron corrosion, the anode reaction can be represented as Fe(s) → Fe²⁺(aq) + 2e⁻, indicating the loss of electrons from iron. Conversely, the cathode reaction often involves the reduction of oxygen, such as O₂ + 4e⁻ + 2H₂O → 4OH⁻, which helps to complete the electrochemical circuit and sustain the corrosion process.