چكيده لاتين :
Kinetics of the oxidation of tris(2,2پŒ-bipyridine)iron(II) sulfate by ceric sulfate was spectrophotometrically studied in an
aqueous sulfuric acid medium. Different methods, including isolation, integration and half-life, were employed to determine the
reaction order. The redox reaction was found to be first-order with respect to the reductant, tris(2,2پŒ-bipyridine)iron(II) sulfate,
and the oxidant, ceric sulfate. Complex kinetics was observed with an increase in the initial concentration of the oxidant. The
influence of the dielectric constant, [H+] and [SO4
2-] on the rate was also investigated. The increase in the dielectric constant and
H+ ion concentration of the medium retard the rate, while an increase in the SO4
2- ion concentration first accelerates the rate, and
then retards the reaction. The effect of each factor, i.e., the dielectric constant, H+ ions and SO4
2- ions, suggests that Ce(SO4)3
2- is
the active species of cerium(IV). A rate law consistent with the observed kinetic data and the proposed mechanism is suggested to
be:
[ ( ) ] [ ( ) ][ ] [ ]
[ ]d i a
t a
IV
d
K K SO
k K K Fe bipy Ce SO
dt
d Fe bipy
.
+ + .
+
. =
2
4
2
2
4
2
1 3
2
3
