1.

Calculate the equivalent weight of KMnO_(4)

Answer»

Solution :`KMnO_(4)` acts as oxidant in acidic, basic and also in neutral medium.
In acidic medium:
`KMnO_(4)+8H^(+) +5e^(-) to K^(+) +MN^(2+)+4H_(2)O`
One molecular of `KMnO_(4)` gains five electrons. Hence the equivalent WEIGHT of `KMnO_(4):`
EQ. `wt=("Mol.wt. of "KMnO_(4))/(5)=(158.04)/(5)=31.608`
In neutral as well as weakly basic medium:
`KMnO_(4)+2H_(2)O+3e^(-) to K^(+)+4OH^(-)+MnO_(2)`
One molecule of `KMnO_(4)` gains three electrons.
Eq. wt `=("Mol.wt. of "KMnO_(4))/(3)=(158.04)/(3)=52.68`
In strongly alkaline medium `: MnO_(4)+E^(-) to MnO_(4)^(2-)`
One molecule of `KMnO_(4)` gains one electron.
Eq. wt `=("MOLE. wt. of "KMmO_(4))/(1)=158.04`


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