Redox reaction

Combustion was the first philosophical and scientific focus of interest among the chemical processes currently known as redox reactions. Fire is among the four elements of matter, according to Greek scientist Empedocles. The phlogiston theory has gained scientific prominence in recent years. G.E. Stahl, a German scientist, initially proposed this hypothesis in 1697. It claimed, as previously stated, that during combustion, matter produces an elementary ingredient called phlogiston. As a result, the release of phlogiston from carbon into the air was perceived as the burning of charcoal.

What is a redox reaction?

As the name suggests redox means reduction and oxidation. The reactions where both oxidation process and reduction process happens at a time in a single reaction is called  Redox reaction.

Examples of redox reaction:

Cellular Respiration – During the respiration reaction, glucose combines with oxygen to produce carbon dioxide and water, releasing energy from the cells. By losing hydrogens, glucose is converted to carbon dioxide, whereas oxygen is converted to water by acquiring hydrogens. 

Combustion: Combustion is an exothermic chemical process that occurs in the presence of an oxidant at extreme temps. When methane is burned in the presence of oxygen in the atmosphere, it produces water and carbon dioxide energy.

Rusting: Rusting of iron is best to be taken as an example of a redox reaction.

Because Rusting of iron undergoes both oxidation and reduction reactions at a time. 

The anode, or electrode where oxidation takes place, is the iron surface in the midst of the water droplet. Iron(II) ions are formed when iron atoms lose electrons.

The electrons rush to the water droplet’s edge, where dissolved oxygen is plentiful. The cathode, or electrode where reduction takes place, is the iron surface there. Oxygen is converted to hydroxide ions after gaining electrons.

Iron(II) hydroxide is formed when the iron(II) ions generated interact with the hydroxide ions.

The combination of oxidation and reduction reaction will be

Types of redox reactions:

There are four types of redox reactions and they are

1. Decomposition Reaction

2. Combination Reaction

3. Displacement Reaction

4. Disproportionation Reaction

1. Decomposition Reaction:

As the name says, decomposition means decomposing the element into two or more elements.

Which means one single compound is divided into two or more compounds.

The general equation of decomposition reaction is

AB → A+B

For example,

2H2O → 2H2 + O2

2. Combination reaction:

Combination means combining. Combining two or more compounds or elements into single element is called combination reactions.

The general equation of combination reaction is

A+B → AB              

For example, H2 + Cl2 → 2HCl

3. Displacement reaction:

Displacement reaction means displacing or replacing one atom in an element with another atom in another element.

The general equation of displacement reaction is

A+BC → AC+B

For example,

CuSO4  + Zn → Cu + ZnSO4

4. Disproportion reaction:

In a disproportion reaction, only one reactant will be both oxidized and reduced is called a disproportion reaction.

For example,

 P4 + 3NaOH + 3H2O → 3NaH2PO2 + PH3

Applications of Redox reactions:

Metallurgy:

Metallurgy can be defined as extraction of metals into pure form.

The chemical reaction of metallurgy example is

 2ZnS+3O2→ 2Zn O + SO2

Here, Zinc sulphide is combined with oxygen and forms zinc oxide and sulphur dioxide.

The oxidation number of zinc on both sides remains the same. But at first the oxidation number of oxygen is zero and when reaction takes place, the oxidation number is converted into -2. Hence reduction process takes place.

Initially, the oxidation number of sulphur is -2, but when the reaction takes place, the oxidation number is increased to +4.Which can be told as oxidation took place. Hence in a single reaction both oxidation and reduction took place. Hence redox reaction is applied in metallurgy.

Combustion:

2Mg + O2→2MgO

Here in the above reaction, we can see Magnesium is combined with oxygen to form MgO.

Initially, the oxidation number of magnesium is zero, after the reaction the oxidation number is increased to +2, which means oxidation took place.

Initially, the oxidation number of oxygen is zero, after reaction the oxidation number is reduced to -2. So we can tell that reduction has taken place. 

Therefore, we can say that combustion is an example of redox reaction.

Batteries:

Also in batteries, we will use redox reactions. For example let us take Daniel cells. Zinc is anode and copper is cathode . At anode, Oxidation reaction takes place and at cathode, reduction reaction takes place.

Zinc loses two electrons and so oxidation takes place.

Whereas, copper takes or gains those two electrons and so reduction takes place. So this can also be taken as an application of the Redox reaction. 

Conclusion:

As the name suggests redox means reduction and oxidation. Both oxidation and reduction reactions take place in a single chemical reaction. One compound will increase its oxidation number and one compound will reduce its oxidation number. Rusting is taken as the best example of redox reaction. Because, when iron is reacted with both water and oxygen, it changes into iron oxide also called rust. There are many types of redox reactions, like decomposition reaction, combination reaction, displacement reaction, and disproportion reaction. The best example of a redox reaction can be taken as electrolysis. Where both losing and gaining of electrons take place.