The enthalpy of hydration of the` Fe^(2+)` ion is `11.4kcal//mol` higher than would be expected if there were no crystal field stabillisation energey Assuming the equo complex to be high spin estimate the magnitude of `Delta_(0)` for `[Fe(H_(2)O)_(6)]^(2+)` ion .

Explanation

`Fe^(2+)` is `t_(2g) ^(4) e_(g)^(2)` in weak field environment
`CFSE = - ( 0.4 xx 4) Delta_(0) + (0.6) xx 2)Delta_(0)`
`=- 1.6 Delta_(0) + 1.2 Delta_(0)` ltbgt ` = - 0.4 Delta_(0)`
`DeltaH_(hyd)` is higher because the energey of the complex lowered b`y -11.4kcal//mol`
`CFSE = - 11.41 kcal//mol = - 0.4Delta_(0)`
`Delta_(0) = (-11. 4)/(0.4) = - 28 .5 kcal//mol`
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