Chapter 18, Problem 18.87QP

Interpretation Introduction

Interpretation:

The oxidation state of gold in the given gold salt has to be found.

Concept Introduction

Oxidation number of an element represents the number of electrons gained or lost by an element during a chemical reaction.  The value of oxidation sate can be positive, negative or zero.

Electrolysis is the process in which the electric current is used for the initiation of a non-spontaneous reaction. The process is widely used for the separation of elements from a mixture or ore.  The process of electrolysis is carried out in an electrolytic cell.

Faradays first law of electrolysis says that the quantity of substance deposited on an electrode is proportional to the charge passed through the solution.

$\text{m = Z}\times \text{Q}$

Where,

$\text{m}$ is the amount of substance liberated

$\text{Q}$ is the quantity of charge passed

$\text{Z}$ is the electrochemical equivalence of the substance

Faradays second law of electrolysis says that when same amount of electricity is passed through different solutions the amount of substance deposited is proportional to their equivalent weight.

The two laws can be summarised as given below

$\text{m = }\left(\frac{\text{Q}}{\text{F}}\right)\left(\frac{\text{M}}{\text{z}}\right)$

Where

$\text{m}$ is the amount of substance liberated

$\text{Q}$ is the quantity of charge passed

$\text{F}$ is Faraday Constant $(96500{\text{Cmol}}^{\text{-1}})$

$\text{M}$ is the molar mass of the substance

$\text{z}$ is the valency of the substance