Difference Between Oxidizing Agent and Reducing Agent

氧化剂和还原剂

Oxidation and reduction reactions are joined together. Where one substance is oxidized another substance reduces. Therefore, these reactions are jointly known as redox reactions. Originally, oxidation reactions were identified as the reactions in which oxygen gas participates.There, oxygen combines with another molecule to produce an oxide. In this reaction, oxygen undergoes reduction and the other substance undergoes oxidation. So basically oxidation reaction is adding oxygen to another substance. For example, in the following reaction, hydrogen undergoes oxidation and hence, oxygen atom has added to hydrogen forming water.

2H₂+ O₂-> 2H₂O

Another way to describe oxidation is as loss of hydrogen. Another alternative approach to describe oxidation is as losing of electrons. This approach can be used to explain chemical reactions, where we can’t see an oxide formation or hydrogen losing. So, even when there is no oxygen, we can explain oxidation using this approach.

Oxidizing Agent

According to the above examples, oxidizing agent or the oxidizer can be defined as the agent who removes electrons from another substance in a redox reaction. Since it removes electrons, other substance will have a higher oxidation number than the reactant. The oxidizing agent then undergoes reduction. For example in the following reaction, magnesium has converted to magnesium ions. Since, magnesium has lost two electrons it has undergone oxidation and chlorine gas is the oxidizing agent.

Mg + Cl₂-> Mg²⁺+ 2Cl^–

In the above reaction between hydrogen and oxygen gases, oxygen is the oxidizing agent. Oxygen is a good oxidizer in reactions. Further, hydrogen peroxide, sulfuric acid, nitric acid, halogens, permanganate compounds, and Tollen’s reagent are some of the common oxidizing agents.

Reducing Agent

Reduction is the opposite of oxidizing. In terms of oxygen transfer, in the reduction reactions oxygens are lost. In terms of hydrogen transfer, reduction reactions take place when hydrogen is gained. For instance, in the above example between methane and oxygen, oxygen has reduced because it has gained hydrogen. In terms of electron transfer, reduction is gaining electrons. So according to the above example, chlorine is reduced.

Reducing agent is a substance which donates electrons to another substance in a redox reaction. Thus, the other substance undergoes reduction and the reducing agent becomes oxidized. Strong reducing agents have the capability to donate electrons readily. When the atomic radius is large, the attraction between the nucleus and the valence electrons weakens; therefore larger atoms are good reducing agents. Moreover, good reducing agents have a low electronegativity and small ionization energies. Sodium borohydride, lithium aluminum hydride, formic acid, ascorbic acid, sodium amalgam, and zinc mercury amalgam are some of the common reducing agents.

氧化剂和还原剂