Composite Reactions & the Steady State Approximation

HALOGENATION OF PROPANONE

Hint

For the proposed mechanism

[Halogenation of Propanone - Mechanism A]
Iodine appears as neither a reactant or a product in the reversible step. Therefore, the overall rate of iodine consumption will equal the rate of iodine consumption in the iodination step:
[Halogenation of Propanone - Mechanism A - Iodination Step]

Overall Rate of Consumption of Iodine {-d[I2]/dt}

For the proposed mechanism

[Halogenation of Propanone - Mechanism A]

The overall rate of consumption of iodine can be expressed as

-d[I2]/dt = + k1[H+][Pk] + k-1[Pe][H+] + k2[Pe][I2]

-d[I2]/dt = - k2[PI][H+][I-]

-d[I2]/dt = + k2[Pe][I2]