Right. Let’s move on to a practical application
of some of the ionic chemistry that we discussed
in the previous module. RedOx reactions are
by far the most important types of reactions
that you’ll come across. They involve the
transfer of electrons from one species to
another. Oxidation is defined as the loss
of electrons. So, this would be, for example,
let’s say, sodium, which is in group 1 as
an element, would be oxidised when it lost
its single outer shell electron.
A reduction is defined as a gain of electrons.
Let us take fluorine. When it, in order to
complete its outer shell, takes on a single
electron, it would be considered to be reduced.
Sometimes an easy way to remember this is
by the mnemonic, oil rig. Oxidation is loss,
reduction is gain.
Oxidation and reduction must occur simultaneously
since, of course, the electrons must go somewhere;
you don’t lose them, there is conservation
So, let’s have a look at one example - the
reaction of iron with a solution of copper
sulphate. It is an example of an oxidation
reduction reaction or a RedOx reaction. The
equation for this is given below on our board.
Iron, as a solid, reacts with a solution of
copper sulphate. Note, aq means it is in water.
And this results in the formation of a solution
of iron sulphate and solid copper is then
Let’s look at this in more detail. What
do we actually mean? The net ionic equation,
if we isolate it, shows that we are losing
two electrons from the iron which we’re
going to add to the copper ion, 2+, to form
So, in this scenario, iron or Fe is lost of
two electrons or deprived of two electrons
which results in the formation of Fe2+ cation.
The copper cation, which is already in solution,
is reduced, gain in two electrons and can
be converted from its 2+ cation to its oxidation
state zero element.
And of course, this would… reaction would
be visible because copper, as an element,
is insoluble in water and would precipitate