Oxidation Number
Chapter Name : Redox Reactions |
Sub Topic Code : 102_11_08_03_08 |
Topic Name : Oxidation Number |
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Sub Topic Name : Limitations Of Concept Of Oxidation Number |
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Introduction
Oxidation number denotes the
oxidation state of an element in a compound.
Limitations:
According to the
concept of oxidation number, none of the species is undergoing any change in
oxidation number in case of the reaction of silicon chloride and silicon
aluminium hydride.
Pre-Requisites:
Oxidising agent,
reducing agent, oxidation, reduction
Activity:
Rust forms when Iron
reacts with oxygen in air in the presence of moisture.
Real Life Question:
How does rust form..?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| 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 |
|---|---|
| Daniel cell | In the Daniel cell, copper and zinc electrodes are immersed in a solution of copper(II) sulfate and zinc sulfate respectively. At the anode, zinc is oxidized. At the cathode, copper is reduced. Then calculate the oxidation of both the reactants. |
Real life uses :
Rust
formation
Places to visit :
Chemistry lab
Practical examples around us
| Examples | Explainations |
|---|---|
| Rusting | Rust forms when Iron reacts with oxygen (air) in the presence of moisture. |
What you learn in Theory:
•
Many a times, it becomes difficult to classify a
reaction as redox reaction according to all the three approaches, viz.,
classical, electronic and oxidation number approach.
To overcome these
limitations, a broader concept of redox processes in terms of changes in
electron density has been proposed.
What you learn in Practice:
According
to the classical approach, many reactions are called as redox reactions.
However, it has been found
that practically it is not possible to do the same by applying the oxidation
number concept.