Question

What is the rate law for the following mechanism?

                        CH₃COOC₂H₅ + H₂O → CH₃COOC₂H₆⁺ + OH^-                  (Slow)

                        CH₃COOC₂H₆⁺          → CH₃COOH + C₂H₅⁺                     (Fast)

                        C₂H₅⁺   +      OH^-        → C₂H₅OH                                   (Fast)

A) Rate = k[CH₃COOC₂H₅][H₂O]²

B) Rate = k[C₂H₅OH]

C) Rate = k[CH₃COOH]

D) Rate = k[CH₃COOC₂H₅]

E) Rate = k[CH₃COOC₂H₅][H₂O]

The answer is E, but could you please give a detailed response on how to get to this answer? Thank you.

Answer 1

rate equation can be written to the slowest step

that why we used to call rate determining step

in the above mechanism slow step is

CH3COOC2H5 + H2O → CH3COOC2H6+ + OH-                  (Slow)

so rate will be

E) Rate = k[CH3COOC2H5][H2O]

but if you talk strictly we will not even consider the concentration H2O because compare to ethyl acetate water concentration is too high so this reaction we used to call as psudo unimolecular reaction