Wednesday, September 4, 2013

Electronic Concept Of Oxidation And Reduction

Oxidation :
       Oxidation is a process in which an atom taking part in chemical reaction loses one or more electrons. Te loss of electrons results in the increase of positive charge ( or ) decrease of negative of the species.
Example :
               Mg         →   Mg2+   +   2e-   ( increase of positive charge )
               Fe2+       →  Fe3+    +   e-       ( increase of positive charge ) 
                Cu        →  Cu2+    +   2e-   ( increase of positive charge ) 
              S2-          →    S      +     2e-     ( decrease of negative charge )

               MnO42-  →   MnO4-   +  e  ( decrease of negative charge ) 
  • Loss of electrons during the reactions are called reducing agents or reductants. In the above equation Mg  , Fe2+  ,  Cu are reducing agents.  
  • Some important oxidizing agents are,  O2 , O3 , H2O2 , Cl2 , HNO3 , KMnO4 ,  etc.

Reduction :
      Reduction is a process in which atom taking part in chemical reaction gains one or more electrons. The gain of electrons results on the decrease of positive charge or increase of negative charge of the species.
Example :

                  Fe3+    +   e-      →   Fe2+      ( Decrease in positive charge )
                  Zn2+   +    2e-   →  Zn           ( Decrease in positive charge )
                   Sn4+   +   2e-   →  Sn2+         ( Decrease in positive charge )  
                       S   +     2e-  →  S2-           ( Increase in negative charge )
                   MnO4-   +  e  → MnO42     ( Increase in negative charge )
  • Gain of electrons during the reactions are called oxidizing agents or oxidants. Sn4+  ,  Zn2+ , Fe3+    are  oxidizing agents.
  • During oxidation acidic nature increases.
  • Burning of coal, rusting of ion and combustion reactions involve oxidation.
  • Just reverse process occurs during reduction. 
  • Some important reducing agents are , H2 , C , H2S , SO2 , SnCl2 , Al, etc.

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