Consider the reaction,
`Cl_(2)(aq) + H_(2)S(aq) rarr S(s) + 2H^(+) (aq) + 2Cl^(-)(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) `Cl_(2) + H_(2)S rarr H^(+) + Cl^(-) + Cl^(+) + HS^(-)` (slow)
`Cl^(+) + HS^(-) rarr H^(+) + Cl^(-) + S` (fast)
(II) `H_(2)S hArr H^(+) +HS^(-)` (fast equilibrium)
`Cl^(+) + HS^(-) rarr 2 Cl^(-) + H^(+) + S` (slow)

Options

A. Only I
B. Only II
C. Both I and II
D. Neither I nor II

Answer

A

Explanation

Since, rate ofr reaction depends upon the concentration of rectant molecules in the rate determing step. Slow step is rate determing step. Slow step is rate determing step.
`therefore` From `(A)r=k[Cl_(2)][H_(2)S]`
and from `(B)r=k[Cl_(2)][HS^(-)]`
Hence, only (A) is correct choice.