Chapter 23, Problem 92A

Interpretation Introduction

Interpretation : To determine the electrode at which the reduction takes place.

Concept Introduction : Reduction is defined as the loss of oxygen and the gaining of electrons. In the case of an electrochemical cell, there are two electrodes present one is the cathode and the other is the anode. In this cell, both oxidation and reduction take place simultaneously resulting in the redox reaction.

Answer to Problem 92A

Reduction takes place in a cathode. The cathode is negatively charged.

Explanation of Solution

If an electrochemical 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.

Since the cathode attracts the cations and the electrons are pumped toward the cathode it will be negatively charged.

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 continuous oxidation and reduction reaction. The electrochemical cell is neutralized by a salt bridge.