Consider the reaction: `Cl_(2) (aq) + H_(2)S(aq) rarr S(s) + 2H^(+) (aq) + 2CI^(-)` (aq) The rate equation for this reaction is rate = `k [Cl_(2) ] [H_(2)S]` Which of these mechanisms is/are consistent with this rate equation.
(I) `CI_(2)+H_(2)S rarrH^(+)+Cl^(-)+CI^(+)+HS^(-)` (slow)
`Cl^(+)+HS ^(−) →H^( +)+Cl ^(−)+ S ` (fast)
(II) `H_(2)S rarrH^(+) +HS^(-)` (fast equilibrium)
`Cl _(2)+HS^(−)→2Cl ^(−)+H^(+)+S ` (slow)

Options

A. I only
B. II only
C. both I and II
D. neither I nor II

Answer

A

Explanation

As the slowest step is the rate determining step so from mehanism I rate =`k[CI_(2)][H_(2)S]`