Chapter 23, Problem 91A

Interpretation Introduction

Interpretation : To determine the source of electric energy in a voltaic cell.

Concept Introduction : In a voltaic cell, simultaneous oxidation and reduction take place resulting in the transfer of electrons between the cathode and the anode that will produce electrical energy.

Answer to Problem 91A

The electrons produced during the redox reaction are the source of electrical energy produced by the voltaic cell.

Explanation of Solution

If a Voltaic cell such as a galvanic cell is considered with copper as a cathode and zinc as an anode, dipped in their respective electrolytes. Zinc will get oxidized and lose electrons and form zinc ions whereas these electrons are gained by the copper ions in the electrolyte and get deposited as copper.

The reaction at the cathode is:

  ${\text{Cu}}^{\text{2+}}{\text{+2e}}^{\text{-}}\to \text{Cu(s)}$

The reaction at the anode is

  $\text{Zn(}s)\to {\text{Zn}}^{\text{2+}}{\text{+2e}}^{\text{-}}$

From this example, it is clear that reduction takes place at the cathode and oxidation takes place at the anode. The electrons transferred during this reaction result in the production of electrical energy.

Conclusion

The electrochemical cell is a cell in which chemical energy is converted into electrical energy. This generation of electrical energy can take place only if there is a continuous transfer of electrons by oxidation and reduction reactions. The electrochemical cell is neutralized by a salt bridge.