One of the most important type of reactions in chemistry is reduction/oxidation reactions. While they seem to be two different forms of reactions, they are not. Its best to describe them as two components of the same process. An oxidation reaction is followed by a reduction and vice versa. In this article, we want to see what a redox (reduction/oxidation) involves.
Like I mentioned above, oxidation and reduction are complementary chemical processes, hence they are treated as one. The underlying principle in redox reactions is that there is usually a transfer electrons between two atoms or ions or compounds. One of the atoms transfers the electrons and the other receives it.
There is no single definition of redox reactions. So many different chemical processes involving specific atoms are described as redox reactions. A steady feature here is that there is a movement of electrons between the reacting atoms or ions. So we will look at some of the examples which are described as redox reactions.
One of the standard definition of redox reactions involves the element oxygen. In this case, oxidation is defined as a reaction where oxygen is added to another atom, ion or compound. Since reduction is a complement of oxidation, then reduction here is a chemical reaction in which oxygen was removed from a compound.
There are oxidizing and reducing agents in each redox reaction depending the roles each atom or compound played. The oxidizing agent refers to the compound that transferred its oxygen to another compound. Then the atom that received the donated oxygen is often referred to as the reducing agent.
Consider the following redox reaction below involving the transfer and receiving of oxygen.
The above is a typical example of oxidation/reduction reaction. Consider what happens here.
Reactants: The reactants here are hydrogen peroxide and Potassium iodide.
Products: The Products are water, Potassium hydroxide and iodine.
Oxidation: Oxidation involves the addition of oxygen to a compound. One of the reactants is Potassium iodide which never had oxygen before the reaction. But after the reaction, it gained oxygen to form potassium hydroxide. So that part of the reaction is known as oxidation. Oxygen was added to a compound.
Reduction: Reduction involves the removal of oxygen from a compound. In the above example, Hydrogen peroxide lost its oxygen and was reduced to water after the reaction. So this part of the reaction is know as reduction. Note that both reduction and oxidation happened in this reaction. Hence the two are complementary processes of the same reaction.
Oxidizing agent: The compound that donated oxygen is the oxidizing agent. In this case, hydrogen peroxide is the oxidizing agent.
Reducing agent: The compound which gained oxygen is described as the reducing agent. In this case, potassium iodide is the reducing agent.
We will consider another reaction that also supports the definition of redox which involves the addition and removal of oxygen
Above is another typical redox reaction defined in terms of addition and removal of oxygen. Lets see how it happened.
Reactants: The reactants here are carbon and mercury (II) oxide
Products: The products are carbon dioxide and mercury
Oxidation: Described in terms of addition of oxidation, we can note here that before the reaction, Carbon had no oxygen. But after the reaction, carbon gained oxygen to form carbon dioxide.
Reduction: Reduction which involves removal of oxygen also took place. Before the reaction, mercury (II) oxide had oxygen which was lost after the reaction. So that part could be described as the reduction aspect of the reaction.
Oxidizing agent: The compound that lost its oxygen is the oxidizing agent. In this instance, mercury (II) oxide is the oxidizing agent.
Reducing agent: The one that gained oxygen is carbon. Hence carbon is the reducing agent.
It is very easy to understand redox reactions defined in terms of the element oxygen when we note how oxygen is involved in any chemical reaction. If there is addition of oxygen and also removal of oxygen in the same chemical reaction, it is defined as redox.
The definition of redox reactions does not end with oxygen alone. Another compound that has this definition centered around it is hydrogen. In the next presentation, we will learn how removal of hydrogen could also be defined as a redox reaction.
Note: All images are designed by the author.
