Chapter 21, Problem 87A

Interpretation Introduction

Interpretation: The electrolytic cell needs to be drawn that is used to plate gold onto an object.

Concept Introduction: In an electrolytic cell, electrical energy is used to generate a non-spontaneous redox reaction. The three components of an electrolytic cell are cathode, anode, and electrolyte. Here, reduction takes place at the cathode, oxidation takes place at the anode, and the electrolyte act as a medium for the exchange of ions between the two electrodes.

Explanation of Solution

In order to plate gold onto an object, the negative electrode of the power source is connected to the object and the positive electrode is connected to the gold metal. Here, gold acts as an anode, and oxidation of gold takes place. Due to the oxidation of the gold, gold ions come to the solution, and the reduction of gold takes place at the cathode where it gets plated on the object.

Thus, the positive charge electrode is the anode where oxidation takes place and the negative charge electrode is the cathode where reduction takes place.

The two half-reactions can be represented as follows:

Anode: $\text{Au}\left(s\right)\to {\text{Au}}^{3+}\left(aq\right)+3e$

Cathode: ${\text{Au}}^{3+}\left(aq\right)+3e\to \text{Au}\left(s\right)$

The flow of electrons takes place from positive electrode to negative.

The electrolytic cell showing gold plating is represented as follows: