Oxidation-Reduction Reactions

Oxidation-Reduction Reactions

(1)  Oxidation: Oxidation is a process which involves; addition of oxygen, removal of hydrogen, addition of non-metal, removal of metal, Increase in +ve valency, loss of electrons and increase in oxidation number.

(i) Addition of oxygen: 2Mg + O2 2MgO

(ii) Removal of hydrogen: H2S+Cl22HCl + S     

(iii) Addition of Non-metal: Fe + S  FeS       

(iv) Removal of metal: 2KI+H2O22KOH+I2

(v) Increase in +ve valency :                  

(vi) Loss of electrons (also known as de-electronation)



 –e–        –e–        –e–        –e–       –e–        –e–       –e–         –e

Loss of electrons

(a)                (Formation of proton)

(b)       (De-electronation of )

(c)         (De-electronation of iron)

(vii)Increase in oxidation number

(a)      (From 0 to +2)

(b)      (From +2 to +3)

(c)        (From –1 to 0)

(2) Reduction: Reduction is just reverse of oxidation. Reduction is a process which involves; removal of oxygen, addition of hydrogen, removal of non-metal, addition of metal, decrease in +ve valency, gain of electrons and decrease in oxidation number.

                 (i)         Removal of oxygen:         

(ii) Addition of hydrogen: 

                 (iii)       Removal of non-metal 


                 (iv)       Addition of metal:  

                 (v)        Decrease in +ve valency 


(a)   (+ve valency decreases)

(b)       (–ve valency increases)

(vi)       Gain of electrons (also known as electronation)


+e–       +e–      +e–      +e–     +e–    +e–     +e–      +e

Gain of electrons

(a)     (Electronation of )

(b)                        (Electronation of )

(c) (Electronation of )

(vii) Decrease in oxidation number

(a)      (From +2 to 0)

(b)             (From +3 to +2)

(c)        (From 0 to –1)

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