Chapter 21, Problem 52A

Interpretation Introduction

Interpretation: Some applications of electrolysis in the field of metallurgy need to be explained.

Concept Introduction: An electrolytic cell is used to convert electrical energy to chemical energy. Here, an electrolytic cell uses electrical energy to make a non-spontaneous redox reaction to go on completion.

Explanation of Solution

Some applications of electrolysis in the field of metallurgy are as follows:

1. Electroplating and electroforming: In an electroplating process, the deposition of a thin layer of metal is made in an object in an electrolytic cell. It is done to protect the surface of the object from corrosion. Here, an object that undergoes electroplating is made the cathode (where reduction takes place) and the metal which is electroplated on the surface of the object is taken as the anode (where oxidation takes place). When direct current is applied, metal ions move from the anode to the object to be plated.
Now, in an electroforming process, an object is reproduced by taking metal from the cathode of a cell. The object is then electroplated with a coating of metal. This is then stripped off of the mold.

2. Electrowinning and electrorefining: In the electrowinning process, the purification of impure metals can be done in electrolytic cells. Here, the reduction of cations of molten salts takes place at the cathode to give pure metals. This process can be used to extract aluminum from its ore.
In the electrorefining process, impure metal made the anode where oxidation occurs. Its oxidation results in the formation of cations, which are then reduced to pure metals at the cathode. It is used to prepare ultrapure silver, copper, and lead metals.