The following mechanism has been proposed for the reaction of NO with H2 to form N2O and H2O: NO1g2 + NO1g2¡N2O21g2 N2O21g2 + H21g2¡N2O1g2 + H2O1g2 (d) The observed rate law is rate = k3NO423H24. If the proposed mechanism is correct, what can we conclude about the relative speeds of the first and second reactions?

Key Concepts

Reaction Mechanism

A reaction mechanism is a step-by-step description of the pathway through which reactants are converted into products. It outlines individual elementary steps, each with its own rate, and helps in understanding how the overall reaction occurs. In this case, the proposed mechanism involves two steps leading to the formation of N2O and H2O from NO and H2.

Rate Law

The rate law expresses the relationship between the rate of a chemical reaction and the concentration of its reactants. It is determined experimentally and can provide insights into the mechanism of the reaction. The given rate law, rate = k[NO]^4[H2]^2, indicates that the rate depends on the concentrations of NO and H2, suggesting that the first step is likely the rate-determining step.

Rate-Determining Step

The rate-determining step is the slowest step in a reaction mechanism that controls the overall rate of the reaction. It is crucial for understanding the kinetics of the reaction. In this scenario, if the observed rate law corresponds to the concentrations of reactants in the first step, it implies that this step is slower than the second step, thus determining the overall reaction rate.