what does it mean when ions are reduced?

You know that an ion is an atom that has gained or lost electrons to from a positive or negative ion.

Loosing an electron in called oxidation

Gaining an electron is called reduction

Whenever you reduce a reagent another reagent is oxidised, and vice versa, because the electron has to come from somewhere.

So for every reduction there is an oxidation.

We call these Reduction-oxidation reactions (Redox reactions for short) and there are always 2 half equations. The half equation that shows the reagent that is reduced = the reduction half equation.

And the half equation that shows the reagent that is being oxidised = the oxidation half equation

Redution is gaining of electrons

So when something is reduced you are adding electrons.

Your Fe3+ is gaining an electron (being reduced) to form Fe2+

This is called the reduction half equation

Fe3+(aq) + e ------> Fe2+(aq)

In this example the electrons are coming from Chloride ions

The chloride ions (Cl-) are losing electrons. This is called oxidation. (oxidation is loss of electrons). The Chloride ions are thus being oxidised

Oxidation half equation

2Cl-(aq) ---------> Cl2(g) + 2e

It is important to balance the number of electrons in the half equations.

You can see that in this case you have only 1 electron being trasferred in the reduction half equation, but there are 2 in the oxidation half equation.

So you need 2 x the reduction half equation to balance the oxidation half equation

2 Fe3+(aq) + 2e ------> 2 Fe2+(aq)

2Cl-(aq) ---------> Cl2(g) + 2e

Then you add the two half equations together to give the full redox equation. The electrons cancel out

2Fe3+(aq) + 2Cl-(aq) ----------> 2Fe2+(aq) + Cl2(g)