Consider the reaction : Cl_(2)(aq)+H_(2)S(aq) to S(s)+2H^(+)(aq)+2Cl^(-)(aq) the rate equation for this reaction is rate=k[Cl_(2)][H_(2)S] Which of these mechanism is/ are consistent with this rate equation? A. Cl_(2)+H_(2)S to H^(+)+Cl^(-)+HS^(-) (Slow) Cl^(+)+HS^(-) to H^(+)+Cl^(-)+S (fast) B. H_(2)S harr H^(+)+HS^(-) (fast equilibirium) Cl_(2)+HS^(-) to 2Cl^(-)+H^(+)+S (Slow)

Consider the reaction : Cl_(2)(aq)+H_(2)S(aq) to S(s)+2H^(+)(aq)+2Cl^

1.	Consider the reaction : Cl_(2)(aq)+H_(2)S(aq) to S(s)+2H^(+)(aq)+2Cl^(-)(aq) the rate equation for this reaction is rate=k[Cl_(2)][H_(2)S] Which of these mechanism is/ are consistent with this rate equation? A. Cl_(2)+H_(2)S to H^(+)+Cl^(-)+HS^(-) (Slow) Cl^(+)+HS^(-) to H^(+)+Cl^(-)+S (fast) B. H_(2)S harr H^(+)+HS^(-) (fast equilibirium) Cl_(2)+HS^(-) to 2Cl^(-)+H^(+)+S (Slow)
Answer» B only Both A and B neither A nor B A only Solution :Since the slow step is the RATE DETERMINING step hence if we consider option (A) we find Rate`=k[Cl_(2)][H_(2)S]` Now, it we consider option (B) we find Rate`=k[Cl_(2)][HS^(-)]` …(i) For equationn `H_(2)S harrH^(+)+HS^(-)` `K=([H^(+)][HS^(-)])/([H_(2)S]) or, [HS^(-)]=(K[H_(2)S])/([H^(+)])` SUBSTITUTING this value in EQUATION (i) we find Rate`=k[Cl_(2)]k([H_(2)S])/([H^(+)])=(k[Cl_(2)][H_(2)S])/([H^(+)])` THUS slow step should involve 1 molecues of `Cl_(2)` and 1 molecule of `H_(2)S` Hence only, mechanism (A) is consistent with the given rate equation