# Oxidation and reduction

### Oxidation

Oxidation has been classically defined as the combination of oxygen or any other electronegative element with another element or compound or as the removal of hydrogen or any other electropositive element from a chemical compound.
 Process of oxidation

#### Combination of oxygen means oxidation

1. When carbon burns in oxygen to produce carbon dioxide. Here oxygen is combined with carbon to produce carbon dioxide and carbon is considered to have been oxidized.
C + O₂ ⇆ CO₂
2. The magnesium metal reacts with chlorine to produce magnesium chloride. In this reaction, magnesium is considered to have been oxidized because magnesium combines with oxygen to produced magnesium oxide.
2Mg + O₂ ⇆ 2MgO
3. When Ferrous Oxide heated in oxygen to produce Ferric Oxide. Here Ferrous oxide is considered to have oxidized.
4FeO + O₂ ⇆ 2Fe₂O₃

#### Combination of an electronegative element

When Chlorine gas passes through the colorless ferrous chloride solution it forms #0050ff Ferric chloride. Here ferrous chloride oxidized by the addition of electronegative element chlorine.
2FeCl₂ + Cl₂ ⇆ 2FeCl₃

#### Removal of Hydrogen means oxidation

1. Manganese dioxide reacts with concentrated hydrochloric acid to produce greenish-#0050ff chlorine gas.
4HCl + MnO₂ ⇆ MnCl₂ + Cl₂ + H₂O
Here hydrogen can remove from HCl to form chlorine gas, hence the removal of hydrogen from HCl indicated that HCl can be oxidized.
2. Hydrogen Sulphide reacts with chlorine to produce Sulphur.
H₂S + Cl₂ ⇆ 2HCl + S
In the above reaction, hydrogen can remove from hydrogen sulfide. Thus hydrogen sulfide oxidized to form sulfur.

#### Removal of electro-positive elements

Potassium iodide reacts with Hydrogen peroxide to produce iodine.
2KI + H₂O₂ ⇆ 2KOH + I₂
In the above reaction, electro-positive metal K can remove from KI to from iodine. Thus KI can be oxidized.

### Reduction

The reduction has been classically defined as the combination of hydrogen or any other electropositive element with another element or compound or as the removal of oxygen or any other electronegative element from a chemical compound.
 Process of reduction

#### Addition of Hydrogen means the reduction

1. Bromine can react with hydrogen to produce HBr.
H₂ + Br₂ ⇆ 2HBr
In the above reaction, Bromine can combine with hydrogen to produce hydrogen bromide. Thus bromine can be reduced.
2. Hydrogen Sulphide reacts with chlorine to produce Hydrogen chloride and Sulphur.
H₂S + Cl₂ ⇆ HCl + S
In the above reaction, chlorine can combine with hydrogen. Thus chlorine can be reduced.

#### Addition of electro-positive elements

2K₃[Fe(CN)₆ + 2KOH + H₂O₂ ⇆ 2K₄[Fe(CN)₆] + 2H₂O + O₂
In the above reaction Potassium ferricyanide combination with electro-positive element K to produce potassium ferrocyanide. Thus potassium ferricyanide can be reduced.

#### Removal of Oxygen means the reduction

When hydrogen can pass through black color heated CuO, Oxygen can remove from CuO to form red color Cu. Thus CuO can be reduced.
CuO + H₂ ⇆ Cu +H₂O

#### Removal of electro-negative elements

Sulfur dioxide gas passes through a #0050ff ferric sulfate solution it turns greenish ferrous sulfate solution.
Fe₂(SO₄)₃ + 2SO₂ + H₂O ⇆ 2FeSO₄ + 2H₂SO₄
In the above reaction ferric sulfate removes sulfate to form ferrous sulfate. Thus ferric sulfate reduced to form ferrous sulfate.

### Oxidation

According to the Electronic concept, oxidation is a process that results in the loss of one or more electrons by atoms or ions. Therefore an oxidizing agent is one that gains electrons and is then reduces to a lower valence.
 Electronic Concept of Oxidation

#### Loss of Electron means oxidation

Na, K, Ca, Al, etc. can losses one or more electrons to form their respective cations.
Na → Na⁺ + e

K → K⁺ + e

Ca → Ca⁺² + 2e

Al → Al⁺³ + 3e
All the above reaction the atoms can lose one or more electrons to form respective cations. Thus all the above reaction is oxidation reaction and all these atoms are oxidized.

#### Loss of Electron by Cation

Fe⁺²(Ferrous), Cu⁺(Cuprous), Sn⁺²(Stannous) ion converted Fe⁺³(Ferric), Cu⁺²(cupric), Sn⁺⁴(Satanic) ion by losses one or more electrons. Thus these cations can be oxidized.
Fe⁺² → Fe⁺³ + e

Cu⁺ → Cu⁺² + e

Sn⁺² → Sn⁺⁴ + e

#### Loss of Electron by Anion

Cl⁻(Chloride), Br⁻(Bromide), I⁻(Iodide), S⁻²(Sulphide) anion can losses one or more electrons to form respective elements. In this reaction, these anions can be oxidized.
2Cl⁻ → Cl₂ + e 2Br⁻ → Br₂ + e

2I⁻ → I₂ + e

S⁻² → S + 2e
From the above Examples, we understand that oxidation is,
1. Oxidation is a process for the conversion of the metal atom to cation.
2. Oxidation is a process for conversation lower valence cation to higher valence cation.
3. Oxidation is a process for the conversation of anion to neutral atom.

### Reduction

According to Electronic concept, the reduction is a process that results in the gain of one or more electrons by atoms or ions. Therefore reducing agent is one that loses electrons and is oxidized to a higher valence.
 Electronic Concept of Reduction

#### Gain of Electron means the reduction

Na⁺, Cu⁺², Fe⁺², Fe⁺³ cations can gain one or more electrons to form respective metals.
Na⁺ + e → Na

Cu⁺² + 2e → Cu

Ca⁺² + 2e → Ca

Al⁺³ + 3e → Al

#### Lower Valence cation from Higher Valence Cation

Fe⁺³(Ferric), Cu⁺²(cupric), Sn⁺⁴(Satanic) ion gaining one or more electrons to form Fe⁺²(Ferrous), Cu⁺(Cuprous), Sn⁺²(Stannous) ion. Thus these cations can be reduced.
Fe⁺³ + e → Fe⁺²

Cu⁺² + e → Cu⁺

Sn⁺⁴ + e → Sn⁺²

#### Accept of electrons by an atom

Chlorine, Bromine, sulfur Oxygen can accept an electron to form a respective anion. In these reactions, these anions can be reduced.
Cl₂ + 2e → Cl⁻

S + 2e → S⁻²

O₂ +4e → O⁻²
From the above discussion, it is clear that the reduction reaction is the reverse reaction of oxidation.

Oxidation and reduction reaction according to old concept with examples and Electronic Concept of Oxidation and Reduction with examples