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Explain why (i) E^(@) for Mn^(3+)//Mn^(2+) couple is more positive than that for Fe^(3+)//Fe^(2+) ? (ii) Ce^(3+) can be easily oxidised to Ce^(4+) ? [Atomic numbers : Mn = 25, Fe = 26 Ce = 58] |
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Answer» Solution :(i) `Mn^(2+)` is more STABLE because of half-filled `(4s^0)5d^(5))` d-orbitals than `Mn^(3+)(4s^(0)3d^(4))` while `Fe^(3+)(4s^(0)3d^(5))` is more stable than `Fe^(2+)(4s^(0)3d^(6))` again because of half-filled d-orbitals. Therefore, `Mn^(3+)` can be easily reduced to `Mn^(2+)` whereas Fe3+ is not easily reduced to `Fe^(2+)`, rather `Fe^(2+)` is more easily oxidised to `Fe^(3+)`. (II) `Ce^(4+)` is more stable than `Ce^(3+)` because of stable ELECTRONIC configuration and higher hydration energy of `Ce^(4+)`, HENCE `Ce^(3+)` is easily oxidised to `Ce^(4+)`. |
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