Cathodic Protection Tester Practice Exam

Which of the following is not required in a corrosion cell?

1. Water

2. Oxygen

3. Electrolyte

4. Metallic path

The correct answer is: Oxygen

In the context of a corrosion cell, oxygen is not strictly required for the creation of corrosion reactions. While oxygen is a common factor that can accelerate corrosion—particularly in aerobic environments—it is not an essential component for all types of corrosion processes. Corrosion can also occur in anaerobic conditions, where microorganisms contribute to the corrosion of metals without the presence of oxygen. In certain cases, other chemical agents or reactants can replace oxygen in facilitating the metal's oxidation. Conversely, a corrosion cell typically requires water to act as an electrolyte, which allows the movement of ions. The presence of an electrolyte is critical for creating the conductive environment necessary for the electrochemical reactions involved in corrosion. Additionally, a metallic path is essential because it allows for the flow of electrons, completing the circuit required for the electrochemical reactions that define a corrosion process. Therefore, the answer reflects the nuanced understanding that while oxygen can contribute to corrosion, its absence does not eliminate the possibility of a corrosion cell operating under different conditions.