Explore BrainMass

# Rate Law mechanism observed

Not what you're looking for? Search our solutions OR ask your own Custom question.

This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!

The rate law for the Brâ€”- catalyzed reaction
Br-
C6H5NH2 + HNO2 + H+ C6H5N2+ + 2H2O

is observed to be rate = = k [H+][HNO2][Br -].

A proposed mechanism is
k1
(1) H+ + HNO2 H2NO2+ (rapid equilibrium)
k-1

k2
(2) H2NO2+ + Br- NOBr + H2O (slow)

k3
(3) NOBr + C6H5NH2 C6H5N2+ + H2O + Br- (fast)

Deduce the rate law for this mechanism and relate the observed rate constant k to the rate constants appearing in the assumed mechanism.

Notes:
1. Step (1) is a rapid equilibrium, meaning k1 and k-1 are much faster than k2.
2. The forward and reverse rates are equal for step (1) since it is an equilibrium; this fact can
be used to get an expression for the concentration of the intermediate H2NO2+.
3. Recall, the reaction orders for elementary reactions are determined by the reaction
stoichiometry.
4. Step (2) is sufficiently slow that it can be considered rate-determining.

Â© BrainMass Inc. brainmass.com December 24, 2021, 8:32 pm ad1c9bdddf
https://brainmass.com/chemistry/physical-chemistry/rate-law-mechanism-observed-286701

#### Solution Preview

The rate law for the Brâ€”- catalyzed reaction
Br-
C6H5NH2 + HNO2 + H+ C6H5N2+ + 2H2O

is observed to be rate = = k [H+][HNO2][Br -].

A proposed mechanism is
k1
(1) H+ + HNO2 H2NO2+ (rapid equilibrium)
k-1

k2
(2) H2NO2+ + Br- NOBr + H2O (slow)

k3
(3) NOBr + C6H5NH2 C6H5N2+ + H2O + Br- (fast)

Deduce the rate law for this mechanism and relate the observed rate ...

#### Solution Summary

The expert deduces the rate law for the mechanism that relates to the rate constant.

\$2.49