1.

Balance the following skeleton equation by the method of Partial Equations : KMnO_(4)+H_(2)SO_(4)+(COOH)_(2) rarr K_(2)SO_(4)+MnSO_(4)+CO_(2)+H_(2)O.

Answer»

Solution :The oxidation of oxalic ACID, `(COOH)_(2)`, by potassium permaganate, `KMnO_(4)`, takes place in the FOLLOWING steps :
(i) `KMnO_(4)` reacts with dil. `H_(2)SO_(4)` to produce nascent oxygen.
`KMnO_(4)+H_(2)SO_(4)rarr K_(2)SO_(4)+MnSO_(4)+H_(2)O+(O)`
By balancing this skeleton equation by Hit and Trial method, we ge
`2KMnO_(4)+3H_(2)SO_(4) rarr K_(2)SO_(4)+2MnSO_(4)+3H_(2)O+5(O)"...(1)"`
(ii) Oxalic acid is oxidised to `CO_(2)` and `H_(2)O` by the nascent oxygen produced in equation (1).
The balanced partial equation for this reaction is :
`(COOH)_(2)+(O)rarr 2CO_(2)+H_(2)O"...(2)"`
To cancel the intermediate product, i.e., nascent oxygen, MULTIPLY equaiton (2) by 5 and ADDING to (1), we have
`2KMnO_(4)+3H_(2)SO_(4)+5(COOH)_(2)rarr K_(2)SO_(4)+2MnSO_(4)+10CO_(2)+8H_(2)O`
This represents the balanced chemical equation for the above reaction.


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