Chapter 20, Problem 60A

Interpretation Introduction

Interpretation:

The anode and cathode reactions in the electrolysis of KI are to be written.

Concept introduction:

In the electrolysis of an ionic solution, the ions move towards the anode or cathode depending on their respective charges to get discharged.

Answer to Problem 60A

Reaction at anode:

$2I^{-}\to I_2+2e^{-}$

Reaction at cathode:

$2H_{2}O+2e^{-}\to H_2+2O{H}^{-}$

Explanation of Solution

At the anode, the oxidation of iodine ions is preferred due to its low electrode potential. At the cathode, the reduction of water is preferred over the reduction of potassium ions because of the lower reduction potential of the former.

Conclusion

Oxidation of iodine ions occurs at the anode and reduction of water molecules occurs at the cathode.