OXIDATION -REDUCTION

Oxidation and reduction in terms of electron transfer
This is easily the most important use of the terms oxidation and reduction at A' level.
Definitions

• Oxidation is loss of electrons.
• Reduction is gain of electrons.

It is essential that you remember these definitions. There is a very easy way to do this. As long as you remember that you are talking about electron transfer:

A simple example
The equation shows a simple redox reaction which can obviously be described in terms of oxygen transfer.

Copper(II) oxide and magnesium oxide are both ionic. The metals obviously aren't. If you rewrite this as an ionic equation, it turns out that the oxide ions are spectator ions and you are left with:

Standard Reduction Potential

Reduction potential is used to calculate the standard electrode potential (E^ocell).
This is the equation most commonly seen in textbooks:
E^ocell = E^o_red + E^o_ox .
where: E^ocell is the standard electrode potential (in volts).
E^o_red is standard reduction potential of the reducing agent.
E^o_ox (standard oxidation potential) is negative of the standard reduction potential of the oxidizing agent.
though the following equation is generally more useful as one is usually only given reduction potentials, not oxidation potentials:


E^ocell = E^o_red - E^o_ox .
or equivalently:
E^ocell = E^o_cathode - E^o_anode
where:
E^ocell is the standard electrode potential (in volts).
E^o_red (E^o_cathode) is standard reduction potential of the reducing agent.
 E^o_ox (E^o_anode) is the standard reduction potential of the oxidizing agent.