Calculating Equivalent Weight of Salts and Redox Reactions

What is the characteristic of an oxidant in a redox system?

What happens when an inert electrode is placed in a redox system with oxidizing properties?

What is the purpose of the Nernst equation in redox systems?

Which of the following is an example of a redox system?

What is the significance of the standard oxidation potential?

What is the role of the platinum electrode in determining the standard oxidation potential?

What is the relationship between the oxidant and its conjugate reductant?

What is the effect of concentration on the oxidation potential of a redox system?

What is the significance of the equilibrium in a redox system?

What is the purpose of the half cell in determining the standard oxidation potential?

Equivalent Weight

Equivalent weight of a salt = molecular weight / number of cations x its valency or molecular weight / number of anions x its valency
Example: Na2SO4, equivalent weight = molecular weight / 2 x 1 or molecular weight / 1 x 2

Equivalent Weight of Oxidant and Reductant

Equivalent weight of oxidant or reductant = molecular weight / number of electrons gained or lost in the reaction
Example: MnO4-, equivalent weight = molecular weight / 5; Fe2+, equivalent weight = molecular weight / 1

Redox Reactions

Redox reactions involve transfer of electrons
Electric current is essentially a transfer of electrons
During redox reactions, a certain amount of electricity is transferred from the reductant to the oxidant

Electrochemical Properties

Electrode potential: a certain potential difference is set up between the metal rod and the solution
Electrolytic solution pressure: tendency of the metal to dissolve
Ionic pressure: passage of metal cations from the solution to be deposited on the metal
Prevailing tendency depends on the chemical nature of the system and the concentration of the solute present

Standard Oxidation Potential

Standard oxidation potential: e.m.f. produced when a half cell consisting of an inert electrode dipped in a solution of equal concentration of both the oxidized and reduced form of a system
Nernst equation for oxidation potential: E 25°C = Eo + 0.0591/n Log [Ox] / [Red]
The magnitude of the potential is a measure of the oxidizing or reducing properties of the system

This quiz covers the concepts of equivalent weight, including the formulas for calculating it, and its application to redox reactions, such as oxidation of ferrous ions by potassium permanganate.