The reaction has the experimental rate law

CHEMISTRY · Subjective · AP · Chemistry · Kinetics · Kinetics

Problem

The reaction 2 NO+H2→N2+H2O2\,\mathrm{NO} + \mathrm{H}_2 \to \mathrm{N}_2 + \mathrm{H}_2\mathrm{O} has the experimental rate law rate=k [NO]2 [H2]\text{rate} = k\,[\mathrm{NO}]^2\,[\mathrm{H}_2]. Two mechanisms are proposed. Mechanism A (1) NO+NO⇌N2O2\mathrm{NO} + \mathrm{NO} \rightleftharpoons \mathrm{N}_2\mathrm{O}_2 (fast) (2) N2O2+H2→N2O+H2O\mathrm{N}_2\mathrm{O}_2 + \mathrm{H}_2 \to \mathrm{N}_2\mathrm{O} + \mathrm{H}_2\mathrm{O} (slow) (3) N2O+H2→N2+H2O\mathrm{N}_2\mathrm{O} + \mathrm{H}_2 \to \mathrm{N}_2 + \mathrm{H}_2\mathrm{O} (fast) Mechanism B (1) NO+H2→HNO+H\mathrm{NO} + \mathrm{H}_2 \to \mathrm{HNO} + \mathrm{H} (slow) (2) H+NO→N2O+H\mathrm{H} + \mathrm{NO} \to \mathrm{N}_2\mathrm{O} + \mathrm{H} (fast) Identify which mechanism (A or B) is consistent with the observed rate law and state your reasoning in one sentence.

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