Study of Redox Reactions

Redox Reaction

In a chemical reaction, when a substance gains oxygen or loses hydrogen, it is said to be oxidised. Such a reaction is known as an oxidation reaction. 

The substance which loses oxygen or gains hydrogen is said to be reduced. Such a reaction is known as a reduction reaction. 

A chemical reaction in which both oxidation and reduction take place is known as a redox reaction. 

Let us observe a few examples. 

Example 1:

Copper forms copper oxide upon heating in the presence of oxygen.

2Cu (s)+O₂ (g)→2CuO (s) 

Copper oxide, in reaction with hydrogen, gives back the copper metal. 

CuO (s) +H₂ (g)→Cu (s)+H₂O (g)

Example 2:

PbO(s) + H₂(g) → Pb(s) + H₂O(l)

Lead oxide Hydrogen Lead Water

In the above reaction, hydrogen is oxidized to water and lead oxide is reduced to lead.

Oxidation and Reduction Reaction

What Is the Oxidation Reaction?

Oxidation may be defined as the loss of electrons from a substance, the addition of oxygen or the more electronegative element, or the removal of hydrogen or the more electropositive element from a substance. 

One of the example of oxidation reaction is: C + O₂ → CO₂ 

What is the Reduction Reaction? 

Like oxidation reactions, reduction reactions are defined as the gain of electrons. Any substance that gains electrons during a chemical reaction gets reduced.

In other forms, the reduction reaction is stated as the addition of hydrogen or a more electropositive element or the removal of a more electronegative element or oxygen from a substance.

2FeCl₃ (aq) + H₂ (g) → 2FeCl₂ (aq) + 2HCl (aq)

Let us now study a redox reaction through a simulation. This experiment aims to study a redox reaction.

The apparatus and chemicals required for this experiment are: 

Apparatus

• China dish
• Spatula 
• A pair of tongs
• Wire gauze
• Burner
• Tripod stand 
• W-tube
• Dropper
• Retort stand

Chemicals

• Zn granules
• Conc. HCl
• Cu powder

The procedure followed for this experiment is as follows: 

1. Take a small amount of copper powder in a china dish and heat it over a burner for some time. 
2. Take a W-tube and put the compound present in the china dish from one end. 
3. At the other end of the W-tube, put some zinc granules. 
4. Add a few drops of conc. HCl from the side of the W-tube containing zinc granules. 
5. Close this open end of the W-tube.
6. Gas will pass through the other side of the W-tube containing a black compound that was formed in the china dish. 
7. Heat this side of the W-tube.

Thus, it can be concluded that, 

1. On heating orange-red copper in the presence of excess air, the copper accepts oxygen and gets oxidised to black-coloured copper oxide.

2Cu (s)+O₂ (g)→2CuO (s) 

2. On passing hydrogen gas over the black-coloured copper oxide, the copper oxide reacts with hydrogen and gets reduced to form orange-red copper. 

CuO (s)+H₂ (g)→Cu (s)+H₂O (g)

FAQs on Study of Redox Reactions