An oxidizing agent is a chemical or element that receives electrons from a different species as part of a redox (oxidation-reduction) reaction.

What is an Oxidizing Agent

An oxidant is a chemical compound that easily transfers oxygen or other atoms in order to get an electron. An oxidizer is a component of a process that releases oxygen or acquires electrons or hydrogen. As it absorbs electrons, the oxidizer is decreased. The reactant, on the other hand, is oxidized by allowing its electrons to be acquired by the oxidizer. Oxygen is the eponymous example of an oxidizing agent.

Oxidizing agents are also referred to as oxidizers or oxidants.

Oxidizing agents can be classified in two ways:

As an electron acceptor: They are chemical compounds whose atoms extract at least one electron from another atom in a chemical reaction. Oxidizing agents are reactants that undergo a reduction in redox reactions, according to this definition.

As an atom-transfer substance: In a chemical reaction, an oxidizing agent is a substance that transfers at least one electronegative atom to a chemical species. Typically, the transferred atom is an oxygen atom. The transfer of an electronegative atom between two reactants is involved in a number of combustion processes and organic redox reactions.

Some Examples

1. Oxygen

Oxygen is the element with the atomic number of 8 and is represented by the symbol O. It is a highly reactive non-metal with good oxidizing capabilities that belongs to the chalcogen group of the periodic table. Metals, in general, tend to create metal oxides when they react with ambient oxygen, owing to oxygen’s high oxidizing power. The majority of combustion processes are found to contain oxygen.

2. Hydrogen Peroxide

The chemical compound hydrogen peroxide has the formula H2O2. It appears to the naked eye as a colorless liquid with a viscosity greater than water. The simplest chemical with a peroxide functional group and an oxygen-oxygen single bond is hydrogen peroxide. It’s used as a disinfectant, bleaching agent, and weak oxidizing agent.

Many different oxidizing agents are routinely employed in industrial settings as well as in people’s daily lives. Household bleach (NaClO), potassium nitrate (KNO3), and sulphuric acid(H2SO4) are examples.

3. Halogens

Halogens are the 17 elements of the periodic table that make up the group. They are regarded to have a significant ability to gain electrons, owing to their high electronegativities in comparison to other groupings of elements.

This indicates that they have the ability to easily attract electrons to their nuclei. Iodine, bromine, chlorine, and fluorine are examples of halogens that are good oxidizing agents. Because of its high electronegativity, fluorine is regarded to be the most powerful elemental oxidizing agent.

4. Oxyanions and Oxyacids

NO3–, IO3–, MnO4–, Cr2O7^2–, and a variety of other oxyanions act as potent oxidizing agents in an aqueous solution. Many of the most powerfully oxidizing oxyanions contain an element in its highest conceivable oxidation state, i.e., with an oxidation number equal to the periodic group number. NO3–, for example, has nitrogen in the +5 oxidation state, while Cr2O7^2– has chromium +6 and manganese +7.

The dichromate ion’s oxidizing capability is used in a laboratory cleaning solution of Na2Cr2O7 in concentrated H2SO4. The organic components in grease are easily oxidized to carbon dioxide. It’s also quite caustic, chews holes in clothing, and needs to be handled with caution.

Another popular oxidizing agent is the dark purple permanganate ion. It is converted to solid dark brown MnO2 in a basic solution. However, in an acidic solution, it generates virtually colorless Mn^2+ (aq).

5. Applications of Oxidizing agent

They are commonly used because of their ability to kill fungi and bacteria while also inactivating viruses. In acidic solutions, group ions such as dichromate (Cr2O7^2-) and permanganate (MnO4-) are powerful oxidizing agents.

Oxidizing agents have a wide range of commercial and industrial uses. Listed below are a handful of these applications:

  1. Fabrics bleaching. 
  2. Water purification.
  3. Used in the combustion of fuel.
  4. Store energy in batteries. 
  5. Rubber vulcanization (increasing the strength and the elasticity of rubber).
  6. In everyday life, it’s utilized to break down colored compounds, such as those found in clothing or hair.
  7. Used in a chemical laboratory for the formation of aldehydes, ketones, and carboxylic acids from alcoholic molecules. 
  8. Many biological functions, such as metabolism and photosynthesis, require oxidizing agents.

What Influences an Oxidizing Agent’s Oxidizing Power?

Oxidizing agents are usually found in their most oxidized states, which means they have a significant ability to gain electrons and undergo reduction. Ions, atoms, and molecules with a high affinity for electrons are thought to be good oxidizers. The greater the oxidizing power, the stronger the electron affinity. 

Fluorine is thought to be the most powerful elemental oxidizer. This could be because fluorine is the most electronegative element in the present periodic table, and hence has the highest attractive force on electrons of all the elements.

In fact, diatomic fluorine (F2) has such a powerful oxidizing activity that it can cause metals like asbestos and quartz (as well as molecules like water) to explode into flames when exposed to it. 

Diatomic oxygen (O2), diatomic chlorine (Cl2), and ozone are some more examples of elemental oxidizing agents (O3). The elemental forms of the second and third most electronegative elements (oxygen and chlorine, respectively) make these oxidizers good electron acceptors.

In a redox process, the standard electrode potential of a half-reaction gives information on the chemical substance’s oxidizing power.

Some chemicals with substantial oxidation states can also be used as oxidizers. The permanganate ion, chromate ion, and dichromate ion are all ionic examples. Nitric acid, perchloric acid, and sulphuric acid are acidic examples of excellent oxidizers.

As the oxidation states of the atoms grow, the electronegativity of the molecules increases, enhancing their propensity to oxidize other substances.

Ashwin Khadka is a PhD Scholar in Nano Energy and Thermofluid Lab in Korea University, Republic of Korea under Korean Government Scholarship Program. He has a Masters Degree in Physics from Tribhuvan University, Kathmandu, Nepal. He is a science enthusiast, researcher and writer.