Question

In a galvanic couple, which metal acts as anode?

• A. The more noble metal
• B. The less noble metal
• C. Both equally
• D. Depends on current

Hint:

In any galvanic couple, the metal that is lower (more active) in the galvanic series corrodes, while the metal that is higher (more noble) remains protected.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks which component metal in a galvanic couple undergoes oxidation (acts as the anode).

Step 2: Key Formula or Approach:
In electrochemistry, the tendency of a metal to lose electrons is determined by its position in the electrochemical or galvanic series.
The metal with the more negative (active/less noble) standard reduction potential will undergo oxidation:
\[ M_{\text{active}} \rightarrow M_{\text{active}}^{n+} + n e^- \]
This electrode is defined as the anode.

Step 3: Detailed Explanation:

• Anodic Dissolution: When two dissimilar metals are in physical or electrical contact in the presence of an electrolyte, a galvanic couple is created.
The less noble (more active) metal has a stronger thermodynamic tendency to corrode. It acts as the anode, releasing electrons and dissolving into the electrolyte.

• Cathodic Protection of the Noble Metal: The released electrons flow through the metallic connection to the more noble (less active) metal.
The more noble metal acts as the cathode, where reduction reactions occur. It is protected from corrosion at the expense of the anode.

• Analysis of Other Options:
- The more noble metal (Option A) always acts as the cathode.
- They cannot act as anodes equally (Option C), and it does not depend on an applied current (Option D) since the process is spontaneously driven by the potential difference.


Step 4: Final Answer:
Therefore, the less noble metal acts as the anode in a galvanic couple, which is Option (B).