Oxidizing Agent

Nov 07, 2022, 16:45 IST

An oxidizing agent (also referred to as an oxidizer or oxidant) is a chemical substance that tends to oxidize other substances, i.e., an increase in the oxidation state of a substance by losing the electrons. Common examples of the oxidizing agents include oxygen, halogens (such as chlorine and fluorine), and hydrogen peroxide (H₂O₂).

Definition

Oxidizing agents can be defined in two ways-

As an electron acceptor – They are chemical substances whose atoms remove one electron from the another atom in the chemical reaction. According to the definition, oxidizing agents are the reactants that undergo a reduction in the redox reactions. An example detailing the electron-accepting properties of an oxidizing agents is provided below.

Substance ‘A’ undergoes oxidation, therefore resulting in an increase in its oxidation number. Whereas the oxidation state of the substance ‘B’ becomes smaller (thus, it gains electrons by undergoing reduction).

As an atom transferring agent – ​​An oxidizing agent is a substance that transfers minimum one electronegative atom to a chemical substance in a chemical reaction. The transferred atom is an oxygen atom. Different combustion reactions and organic redox reactions consist of the transfer of an electronegative atom between the two reactants.

In the example mentioned above, the Fe₂O₃ molecule acts as an oxidizer by transferring an electronegative oxygen atom to the carbon monoxide molecule.

Factors Affecting the Oxidizing Power of an Oxidizing Agent

Oxidizing agents typically exist in their highest possible oxidation states and also have a strong tendency to gain an electrons and undergo reduction. Ions, atoms, and molecules with strong electron affinity are considered good oxidizing agents. As stronger the electron affinity, the greater the oxidizing power.

Elemental fluorine is considered the strongest basic oxidizing agent. This is possible because the fluorine is the most electronegative element in modern periodic table and exerts the strongest attractive force on electrons of any element. The oxidizing power of an F₂ (diatomic fluorine) is most strong enough to cause the metals such as quartz and asbestos (and even molecules such as water) to ignite when exposed to it.

Some examples of elemental oxidizing agents include diatomic chlorine (Cl₂), diatomic oxygen (O₂), and ozone (O₃). These oxidants are primary forms of both the second and the third most electronegative elements (chlorine and oxygen), also making them good electron acceptors.

Standard electrode potential of the half-reaction in the process of redox provides insight into the oxidizing power of a chemical. Below is an example of the ranking of some oxidizing agents in terms of their oxidizing powers.

Some compounds that exhibit the large oxidation states can be considered good oxidizing agents. Ionic examples include the chromate ion, the permanganate ion, and the dichromate ion. An acidic examples of good oxidizers include perchloric acid, sulphuric acid, and nitric acid. The electronegativity of a molecules increases with the increase in an oxidation states of atoms, increasing their ability to oxidize the other substances.

Examples of Oxidizing Agents

1. Halogens

Group 17 elements of the periodic table is referred to as halogens. They have a strong ability to gain a electrons, attributed to their high electronegativities compared to elements from other groups. This means that they can easily attract electrons to their respective nuclei. Examples of good oxidizing agents of halogens include iodine, bromine, chlorine, and fluorine. As stated earlier, fluorine is considered the strongest elemental oxidizing agent due to its strongest electronegativity.

2. Oxygen

Oxygen is an element with the atomic number 8 and is also denoted by the symbol "O." It referred to the group of chalcogen of the periodic table of elements and is a highly reactive nonmetal with the good oxidizing properties. Metals tend to form the metal oxides by reacting with the atmospheric oxygen due to its strong oxidizing power. Oxygen has been observed to be a component of most combustion reactions.

3. Hydrogen peroxide

It is a chemical compound with the formula H₂O₂. To the human eye, it appears as a colorless liquid that has a higher viscosity than water. Hydrogen peroxide is the simplest compound with a peroxide functional group with an oxygen-oxygen single bond. It finds its use as a weak oxidizing agent, disinfectant, and bleaching agent.

Many other oxidizing agents are commonly used in industry and people's daily lives. Examples include household bleach (NaClO), potassium nitrate (KNO₃), and sulfuric acid (H₂SO₄).

Applications of Oxidizing Agents

Oxidizing agents have several commercial and industrial applications. Some of these applications are mentioned below:

• Bleaching of fabrics
• Purification of water
• Combustion of fuel involves the use of an oxidizing agent
• Storage of energy in batteries
• Vulcanization of rubber (increasing the strength and the elasticity of rubber)
• Oxidizing agents are vital to many biological processes, such as photosynthesis and metabolism.
• Many organisms make use of the electron acceptors, or oxidizers, to collect more energy from the redox reactions, such as in the hydrolysis of glucose process.

Frequently Asked Questions (FAQs)

Q1. What makes something a good oxidizing agent?

Ans. Ions, atoms, and the molecules have an unusually large affinity for electrons tend to be good oxidizing agents. Elemental fluorine, for example, is the strongest common oxidizing agent.

Q2. What is the most commonly used oxidizing agent?

Ans. The most common oxidizing agents are halogens—such as chlorine (Cl₂), fluorine (F₂), and bromine (Br₂)—and certain oxy anions, such as the permanganate.

Q3. Which is strongest oxidizing agent?

Ans. Fluorine

Q4. What is the weakest oxidizing agent?

Ans. Li⁺ is the weakest oxidizing agent as it has most negative standard reduction potential.

Q5. What chemicals are strong oxidizing agents?

Ans. Few are the oxidizing chemicals.

• Ammonium perchlorate
• Bromine
• Chromic acid
• Dibenzoyl peroxide
• Hydrogen peroxide
• Perchloric acid
• Sodium perchlorate