Oxidation Number
Chapter Name : Redox Reactions |
Sub Topic Code : 102_11_08_03_06 |
Topic Name : Oxidation Number |
|
Sub Topic Name : Balancing Of Redox Reactions |
|
Introduction
Oxidation number denotes the oxidation state of an
element in a compound.
Pre-Requisites:
Oxidising agent, reducing agent, oxidation, reduction
Activity:
The reaction between hydrogen peroxide and manganate(VII)
ions
Real Life Question:
What is Rust..?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Oxidation Number Method | This method is based on the change in the oxidation number of reducing agent and the oxidising agent. |
| Half Reaction Method | In this method, the two half equations are balanced separately and then added together to give balanced equation. |
| Reducing agent | A reagent which lowers the oxidation number of an element in a given substance. These reagents are also called as reductants. |
| Oxidising agent | A reagent which can increase the oxidation number of an element in a given substance. These reagents are called as oxidants also. |
| Oxidation | Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom, or ion. |
| Reduction | Reduction is the gain of electrons or a decrease in oxidation state by a molecule, atom, or ion. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Rust | Rust is the oxidized form of Iron |
Real life uses :
Balancing
a chemical equation helps to determine how much of a substance can form with
how much reactants
Places to visit :
Garden, window rods,
fences
Practical examples around us
| Examples | Explainations |
|---|---|
| rust | Rust forms when Iron reacts with air in the presence of moisture |
What you learn in Theory:
•
Two
methods are used to balance chemical equations for redox processes:
1.
Half reaction method
Oxidation number
method
What you learn in Practice:
·
Redox equations are
often so complex that fiddling with coefficients to balance chemical equations
doesn’t always work well. Chemists have developed an alternative method (in
addition to the oxidation number method) that is called the ion-electron (half-reaction)
method.
In the ion-electron
method, the unbalanced redox equation is converted to the ionic equation and
then broken down into two half-reactions — oxidation and reduction. Each of
these half-reactions is balanced separately and then combined to give the
balanced ionic equation.