In a galvanic pair, which metal will corrode first?

In a galvanic pair, which metal will corrode first?

• A. The anodic metal
• B. The cathodic metal
• C. Neither
• D. Only with electricity

Answer: (A)

Two metals in electrical contact in an electrolyte form a galvanic couple, and electrons flow from the more active metal to the less active metal. The metal that loses electrons is the anodic metal and it undergoes oxidation, which is the corrosion process. The cathodic metal accepts electrons and is protected from corrosion. So the anodic metal corrodes first. The choice that asserts the cathodic metal corrodes first or that neither corrodes isn’t correct, and external electricity isn’t required—the corrosion is spontaneous due to the natural electrochemical potential difference.

Two metals in electrical contact in an electrolyte form a galvanic couple, and electrons flow from the more active metal to the less active metal. The metal that loses electrons is the anodic metal and it undergoes oxidation, which is the corrosion process. The cathodic metal accepts electrons and is protected from corrosion. So the anodic metal corrodes first. The choice that asserts the cathodic metal corrodes first or that neither corrodes isn’t correct, and external electricity isn’t required—the corrosion is spontaneous due to the natural electrochemical potential difference.