The complexation of `Fe^(2+)` with the chelating agent dipyridyl has been studied Kinetically in both the forward and reverse direction, For the complexation reaction `Fe^(2+)+3` dipy `rarr [Fe(dipy)_(3)]^(2+)`, the rate of formation of the complex at `25^(@)C` is given by
Rate `= (1.45 xx 10^(13) L^(3) mol^(-3) s^(-1)) [Fe^(2+)][dipy]^(3)` and for the reverse of the above eqaution, the rate of disappearance of the complex is
`(1.22 xx 10^(-4) s^(-1)) [Fe(dipy)_(3)]^(2+]`
What is `K_(s)`, the stability constant for the complex ?

Explanation

At equilibrium, the rate of forward reaction `=` rate of backward reaction
`:. R_(f) = R_(b)`
`[1.45 xx 10^(13)L^(3)mol^(-3)s^(-1)] [Fe^(2+)][dipy]^(3)`
`= (1.22 xx 10^(-4) s^(-1)) [Fe(dipy)_(3)]^(2+)`
`:. K_(s) = (R_(f))/(R_(b)) = ([Fe(dipy)_(3)]^(2+))/([Fe^(2+)][dipy]^(3)) = (1.45 xx 10^(13))/(1.22 xx 10^(-4)) = 1.19 xx 10^(17)`