REDOX reactions are reactions that involves both Reduction & Oxidation simultaneously.
There are 4 ways to look at whether a substance has been oxidised or reduced, and they are:
1. Gain/Loss of Oxygen atoms
2. Gain/ Loss of Hydrogen atoms
3. Gain/Loss of Electrons
4. Increase/Decrease in Oxidation States/Numbers
Today we will discuss Oxidation / Reduction based on oxygen atoms.
When a substance gains oxygen in a chemical reaction, we say it has been oxidised. The reaction is called OXIDATION.
When a substance loses oxygen in a chemical reaction, we say it has been reduced. The reaction is called REDUCTION.
E.g. Magnesium reacts with copper (II) oxide to produce magnesium oxide and copper metal.
Mg(s) + CuO(s) –> MgO(s) + Cu(s)
From the above equation, you can see that copper (II) oxide has lost oxygen, so it has been REDUCED.
Magnesium, on the other hand, has gained oxygen and so has been OXIDISED.
Now, the copper (II) oxide is said to be an OXIDISING AGENT because it has given oxygen to magnesium and caused the oxidation of magnesium.
The magnesium, on the other hand, is said to be a REDUCING AGENT because it has taken oxygen from copper (II) oxide and caused the reduction of copper (II) oxide.
In the above chemical reaction, we say it is a REDOX Reaction since both OXIDATION and REDUCTION occurs simultaneously.
Note:
An OXIDISING AGENT helps the other substance to get OXIDISED, and itself gets REDUCED.
A REDUCING AGENT helps the other substance to get REDUCED, and itself gets OXIDISED.
Hope you find the above discussion on REDOX Reactions (based on Oxygen atoms) useful. Feel free to share it with your friends that are taking O-Level Chemistry (or IGCSE, IB and IP Chemistry).
Hi Faatimah,
You can refer to the following post which i had posted previously.
https://www.simplechemconcepts.com/tips-on-assigning-oxidation-number-or-states/
It is on “5 Rules to Assign Oxidation States” in Redox Reactions.
Hope you will find it useful towards your Chemistry learning.
To Your Chemistry Success,
Sean Chua
Hello there I’m a student about to have my o level examinations in the coming August/september I cannot understand how to know the oxidation number of elements.
Thank you .l have been helped so much to have a better understanding on this subject.