Question

Chlorine reacts with hydrogen sul de in aqueous solution Cl2(aq) + H2S(aq) 88n S(s) + 2 H1(aq) + 2 Cl2(aq) in a second-order reaction that follows the rate expression rate = k[Cl2 ][H2S] Which, if any, of the following mechanisms are consistent with the observed rate expression?
A) CI2+H2S→H++Cl−+Cl++HS−(slow),Cl++HS−→H++Cl−+S(fast).
B) H2S↔HS−+H+(fastequilibrium),HS−+CI2→2CI−+S+H+(slow).
C) H2S↔HS−+H+(fast equilibrium),H++Cl2↔H++CI−+CI+(fast equilibrium),CI++HS−→H++CI−+S(slow)

Answer 1

Answer:

Option A

Explanation:

The knowledge of rate law is applied.

From the rate law equation ; r = K [Cl2] [H2S]

From the options, Mechanism A is quite consistent with the rate law equation

it should be noted that rate law can only be written for a slow reaction as this is the rate determining step of the reaction.

Mechanism B and Mechanism C are not consistent with the rate law equation. from the rate law equation of mechanism A, it is the only consistent one with the rate law equation as such the correct option is A.