Question

What are electrochemical principles of metallurgy? Explain with a suitable example.

Answer 1

Electrolysis or the addition of a reducing element are the two methods used to reduce metal ions in solution or in the molten state. Electrochemical principles form the basis of the reduction methods.

We know that the change in the system’s Gibbs free energy is connected to the electrode potential E° of a redox pair (M/Mⁿ⁺) as:

ΔG° = −nE°F    ...(i)

Where n represents how many electrons are involved in the redox process. More negative electrode potential values are seen in more reactive metals. It is therefore very difficult to minimise them. According to equation (i), the value of ΔG° will be negative if there is a positive difference between the E° values of the two redox couples. The more reactive metal will enter the solution in this situation, while the less reactive metal will exit it. To put it another way, the more reactive metal will push out the less reactive metal in this situation. For instance,

\[\ce{Cu^{2+}_{ (aq)} + \underset{metal}{\underset{More reactive}{Fe_{(s)}}} -> \underset{metal}{\underset{Less reactive}{Cu_{(s)}}} + Fe^{2+}_{ (aq)}}\]

Mⁿ⁺ ions are released and deposited at the cathode, or negative electrode, during the electrolysis process. Therefore, electrodes should be manufactured of appropriate materials taking into account the reactivity of the metal produced. Sometimes, a flux is required to increase the conductivity of the molten mass.