Identify the substances that are oxidised and the substances that are reduced in the following reactions.

(i) 4Na(s) + O 2 (g) → 2Na 2 O(s)

(ii) Cu(s) + H 2 (g) → Cu(s) + H 2 O(l)

 

Answer

Addition of Oxygen to a Substance or removal of Hydrogen from a substance is called Oxidation.

 

Removal of Oxygen from a substance or addition of Hydrogen to a substance is called Reduction.

 

(i) 4Na(s) + O 2 (g) → 2Na 2 O(s)

 

Oxygen is added to Na, and it gets oxidized to Na 2 O.

Therefore, Na gets oxidized .

One atom of Oxygen is removed from O 2 , and it gets reduced to Na 2 O.

Therefore, O 2   gets reduced.



(ii) CuO(s) + H 2 (g) → Cu(s) + H 2 O(l)

 

Oxygen is added to H 2 , and it gets oxidized to H 2 O.

Therefore, H 2 gets oxidized .

Oxygen is removed from CuO, and it gets reduced to Cu.

Therefore, CuO gets reduced.



  1. Class 10
  2. Chapter 1 Class 10 - Chemical Reactions and Equations (Term 1)

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CA Maninder Singh
CA Maninder Singh is a Chartered Accountant for the past 11 years and a teacher from the past 11 years. He teaches Science, Accounts and English at Teachoo