CBSE Class 10 Answered

Redox Reaction:

A chemical reaction in which loss of electrons and gain of electrons occur simultaneously is called a redox reaction.  

Example: 

  

In this reaction, hydrogen acts as a reducing agent and reduces copper oxide to copper. This is a reduction reaction. 

Reduction: Cu⁺² + 2e⁻→ Cu 

Simultaneously, copper oxide acts as an oxidising agent and oxidises hydrogen to water. This is an oxidation reaction. 

Oxidation: 2H - 2e⁻ → 2H⁺ 

The O.N. of S increases from -2 to 0. So it is undergoing oxidation and O.N. of Cl₂ decreases from 0 to -1. So it is undergoing reduction. Therefore it is a redox reaction.

CuO + H₂ → Cu +H₂O

In this redox reaction, CuO is getting reduced to Cu since Oxygen is getting removed. So, the conversion of CuO to Cu is reduction reaction. H₂ is getting oxidised to H₂O. So, it is oxidation reaction.

Fe_(s) + CuSO_4(aq) → FeSO_4(aq) + Cu_(s)

Oxidation state of Fe changes from 0 to +2 and oxidation state of Cu changes from +2 to 0.

MnO₄^-+ I^- → MnO₂ + I₂

Here I- is oxidised to I2 and MnO4 - is reduced to MnO2.

Pb + PbO₂ + 2H₂SO₄ → 2PbSO₄ + 2H₂O

In this reaction, Pb is getting oxidised to PbSO₄ and PbO₂ ias reduced to PbSO₄.