Chapter 21, Problem 71A

Interpretation Introduction

Interpretation: The reason for use of direct current and not alternating current in the electroplating of metals needs to be explained.

Concept Introduction: In a redox reaction, reduction and oxidation take place simultaneously. Here, oxidation takes place at the anode and reduction takes place at the cathode.

Explanation of Solution

In the electroplating of metals, two reactions that are oxidation and reduction take place. Here, the plating of a metal onto the other takes place to prevent corrosion. In this process, the first metal from the anode is dissolved and plated onto the cathode. Here, oxidation takes place at the anode resulting oxidizing and dissolving of metal in the electrolyte solution. At the cathode, the metal ions (dissolved metal) get reduced to solid metal and plated on the desired metal. Here, direct current is used as it flows only in one direction. If an alternating current is used for the process, the reactions occurring at the anode and cathode would reverse constantly and the electroplating process cannot be completed.