Crystal field splitting energy `(CFSE)` for the complex `[Cr(H_(2)O)_(6)]^(2+)` is when `P =20925cm^(-1)` and `Delta_(0) = 10462.5cm^(-1)(1kJmo1^(-1) = 83.7 cm^(-1))` .

Options

A. `a.-75kJmo1^(-1)`
B. `b.75kJmo1^(-1)`
C. `c.750kJmo1^(-1)`
D. `d.-750 kJ mo1^(-1)`

Answer

a

Explanation

`Delta ltP` weak field no pairing high spin state
Octahedral complex `CN =6`
`Cr = 3d^(5) 4s^(1) ,Cr^(+2) = 3d^(4)` ,Structure `3(t_(2g)^(2) e_(g)^(1))`
`P = (20925 cm^(1-))/(83. 7) =250 kJmo1^(-1)`
`Delta_(0) = (10462.5 cm^(1))/(83 .7) = 125 kJ mol e^(-1)`
`CFSE = ( 0.4 xx 3 +0.6)Delta_(0) = - 0.6Delta_(0) = -0.6 xx 125`
`=- 75kJmo1^(-1)` .