Oxidizing and reducing agents

Oxidizing and reducing agents We have seen that redox reactions always involve the simultaneous oxidation of one reactant with the reduction of another as electrons are transferred between them. The reactant that becomes reduced (by accepting electrons) is called the oxidizing agent, as it causes oxidation of the other reactant. The reactant that becomes oxidized (by giving up electrons) is called the reducing agent, as it causes reduction of the other reactant. Sometimes the terms reductant and oxidant are used in place of reducing agent and oxidizing agent, respectively.

Oxidizing and reducing agents

More reactive metals are stronger reducing agents Not all oxidizing and reducing agents are of equal strength. Some are stronger than others, depending on their tendencies to gain or lose electrons. Metals have a tendency to lose electrons, pushing their electrons on to another substance. So, more reactive metals lose their electrons more readily and are stronger reducing agents than less reactive metals. We can check to see if one metal is able to reduce another metal by placing it in a solution of another metal.

More reactive metals are stronger reducing agents For example: If we place a piece of zinc metal in a solution of copper sulfate, a reaction will occur. What is happening is that the Cu2+ ions are being displaced from solution (precipitates as Cu) as they are reduced by Zn. At the same time, the Zn dissolves as it is oxidized to Zn2+.

More reactive metals are stronger reducing agents We can write the equation without showing the sulfate ions (these are spectator ions). Because zinc has reduced the copper, it is a stronger reducing agent than copper and a more reactive metal. It has the strength to “force” the copper ions to accept the electrons. We can confirm this by trying the reaction the other way around, with a piece of copper metal in a solution of zinc sulfate solution. There will be no reaction, as the copper is not strong enough to force the zinc to accept its electrons.

More reactive metals are stronger reducing agents

The Activity series

More reactive non-metals are stronger oxidizing agents In a similar way, the different strengths of non-metals as oxidizing agents can be compared. For example, the halogens react by gaining electrons (becoming reduced) and forming negative ions, so they act as oxidizing agents by removing electrons from other substances.

More reactive non-metals are stronger oxidizing agents