Question

In order to protect iron from corrosion, which one will you prefer as a sacrificial electrode, Ni or Zn? Why? (Given standard electrode potentials of Ni, Fe, and Zn are -0.25 V, -0.44 V, and -0.76 V, respectively.)

(a) Ni and provide justification
(b) Zn and provide justification
(c) Ni without justification
(d) Zn without justification

Answer 1

Zinc is preferred over Nickel as a sacrificial electrode to protect iron from corrosion due to its more negative standard electrode potential, which makes it oxidize more readily than iron, serving as the anode and providing cathodic protection.

Step-by-step explanation:

When choosing a sacrificial electrode for protecting iron from corrosion via cathodic protection, one would prefer using Zn over Ni. This decision is based on the standard electrode potentials of each metal, with Ni having a potential of -0.25 V, Fe (iron) -0.44 V, and Zn -0.76 V. Zinc's more negative potential compared to iron means that it is more easily oxidized. Consequently, Zn acts as the sacrificial anode, corroding in the place of Fe. Using a metal like Zn ensures that the iron becomes the cathode and is protected from corrosion as the Zn anode is oxidized preferentially.