Oxidation Number
Chapter Name : Redox Reactions |
Sub Topic Code : 102_11_08_03_07 |
Topic Name : Oxidation Number |
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Sub Topic Name : Redox Reactions As The Basis For Titrations |
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Introduction
Oxidation number denotes the oxidation state of an element in a compound.
Pre-Requisites:
Oxidising agent, reducing agent, oxidation, reduction
Activity:
An example of a redox titration is treating a solution of iodine with a reducing agent and using starch as indicator. Iodine forms an intensely blue complex with starch. Iodine (I2) can be reduced toiodide (I?) by e.g. thiosulphate (S2O32?), and when all iodine is spent the blue colour disappears.
Real Life Question:
Why indicator is being used in titration?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Redox indicator | A redox indicator is a compound which can undergo a redox reaction and change colour depending on the potential of the solution. |
| 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 |
|---|---|
| Burette, indicator | • Titration uses a burette which allows you to know the volume of the titrant being added. • A reaction is complete when the color changes (called the endpoint). |
Real life uses :
• In oxidimetric titrations the oxidising agents are used to determine the reducing and while is reductimetric agents are employed for the determination of oxidising agents.
Places to visit :
Chemistry lab.
Practical examples around us
| Examples | Explainations |
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What you learn in Theory:
• Most data to do the calculations for the stoichiometry comes from doing an experiment called a Titration.
What you learn in Practice:
• In redox systems, the titration method can be adopted to determine the strength of a reductant/oxidant using a redox sensitive indicator.