Redox Chemistry

GCSE Redox Chemistry

Redox equations are a big part of all chemistry since this explains the chemistry behind some of the chemical reactions. It must be noted that not all chemical reactions are redox reactions.

In order to see whether a reaction is a redox reaction or not, and to check what has been reduced or oxidized the following steps can be followed:

• If an atom combines with Hydrogen then it is reduced while if it combines with Oxygen it would be oxidized.
• An acronym OIL RIG can be used. This means that Oxidation is the loss of electrons while reduction is gain of electrons.
• The most important definition is that which states that oxidation is an increase in the oxidation number while reduction is a decrease in oxidation number. The oxidation number can be said to be the valency of the atom in the compound.

Oxidation numbers

In order to ensure that redox reactions are easy to follow the following oxidation numbers should be known, especially due to the fact that these values are the same as the valency.

Grp 1 metals	Always +1
Grp 2 metals	Always +2
Hydrogen	Always +1 except when bonded to a grp 1 metal where it would be -1
Oxygen	Always -2
Fluorine	Always -1
Compounds	Total 0
Elements	Always 0
Ions	Equal to the charge

Definitions

There are two important definitions:

Oxidising Agent:  An oxidizer is any compound that enables another element to be oxidized, while it itself would be reduced. A substance that takes electrons.

Reducing Agent: A reducer is any compound that enables another element to be reduced, while it itself would be oxidised. A substance that donates electrons.

Constructing Redox Equations

Acidic Conditions

1. Balance the atoms
2. Balance the Oxygens by adding H₂O
3. Balance the Hydrogens by adding H⁺
4. Balance the charge by adding e^–
5. Balance the electrons on the reduction and oxidation equations by using cross multiplication

Basic Conditions

1. Balance the atoms
2. Balance the Oxygens by adding H₂O
3. Balance the Hydrogens by adding H⁺
4. Balance the charge by adding e^–
5. Replace the H⁺ by adding OH^– on both sides
6. Balance the electrons on the reduction and oxidation equations by using cross multiplication

Redox Reactions Questions