Chapter 21, Problem 39A

Interpretation Introduction

Interpretation: The electrical potential of a voltaic cell needs to be explained.

Concept Introduction: A voltaic cell is an electrochemical cell in which chemical energy is converted to electrical energy. This is due to the tendency of different metals to lose electrons.

Explanation of Solution

For a voltaic cell, electrical or electrode potential is defined as a measure of the ability of the cell to produce an electric current. It is measured in volts (V). For an isolated half-cell, electrode potential cannot be calculated. When two half-cells are connected to form a voltaic cell, the difference in the potential is measured.

This electric potential is due to competition for electrons between two half-cells. Here, one half-cell has a greater tendency to gain electrons thus, reduction occurs. On the other hand, one half-cell has a greater tendency to lose electrons thus oxidation takes place. A reduction electrode potential is defined as the tendency of reduction taking place at the electrode. Here, reduction takes place in the half-cell with a higher reduction potential and oxidation takes place in the half-cell with a lower reduction potential. The difference between the reduction electrode potential of two half-cells is the electrode potential of the cell.