Increasing which factors together will decrease corrosion rate?

Increasing which factors together will decrease corrosion rate?

• A. Dissolved Oxygen and Alkalinity
• B. DO and pH
• C. DO and Alkalinity
• D. Dissolved Oxygen and pH

Answer: (C)

Corrosion rate is influenced by how much oxygen is available to drive the metal’s oxidation and by how well the water can resist pH changes that accelerate dissolution. When alkalinity is higher, the water has better buffering capacity, so its pH stays more stable even as metals begin to corrode. A stable, slightly alkaline environment helps form and maintain protective oxide films on metal surfaces, which slow further corrosion. At the same time, some dissolved oxygen is present to form those protective films rather than allow rapid, uncontrolled attack. Together, higher dissolved oxygen and higher alkalinity promote passivation and a stable pH, which reduces the rate at which corrosion occurs. The other pairings either rely on pH changes alone or involve oxygen without the buffering that alkalinity provides, making them less consistently protective.

Corrosion rate is influenced by how much oxygen is available to drive the metal’s oxidation and by how well the water can resist pH changes that accelerate dissolution. When alkalinity is higher, the water has better buffering capacity, so its pH stays more stable even as metals begin to corrode. A stable, slightly alkaline environment helps form and maintain protective oxide films on metal surfaces, which slow further corrosion. At the same time, some dissolved oxygen is present to form those protective films rather than allow rapid, uncontrolled attack. Together, higher dissolved oxygen and higher alkalinity promote passivation and a stable pH, which reduces the rate at which corrosion occurs. The other pairings either rely on pH changes alone or involve oxygen without the buffering that alkalinity provides, making them less consistently protective.