The experimental rate law for the reaction NO2+CO ⟶CO2+NO is rate =k[NO2]^2. If the mechanism is

step 1 So here we're given a specific chemical reaction that has a rate law equal to k times the concen

The experimental rate law for the reaction NO2+CO ⟶CO2+NO is...

The experimental rate law for the reaction $$ \mathrm{NO}_{2}+\mathrm{CO} \longrightarrow \mathrm{CO}_{2}+\mathrm{NO} $$ is rate $=k\left[\mathrm{NO}_{2}\right]^{2}$. If the mechanism is $$\begin{array}{rlr}2 \mathrm{NO}_{2} & \longrightarrow \mathrm{NO}_{3}+\mathrm{NO} & (s l o w) \\ \mathrm{NO}_{3}+\mathrm{CO} \longrightarrow & \mathrm{NO}_{2}+\mathrm{CO}_{2} & \text { (fast) } \end{array}$$ show that the predicted rate law is the same as the experimental rate law.

The experimental rate law for the reaction $$ \mathrm{NO}_{2}+\mathrm{CO} \longrightarrow \mathrm{CO}_{2}+\mathrm{NO}
$$ is rate $=k\left[\mathrm{NO}_{2}\right]^{2}$. If the mechanism is $$\begin{array}{rlr}2 \mathrm{NO}_{2} & \longrightarrow \mathrm{NO}_{3}+\mathrm{NO} & (s l o w) \\ \mathrm{NO}_{3}+\mathrm{CO} \longrightarrow & \mathrm{NO}_{2}+\mathrm{CO}_{2} & \text { (fast) } \end{array}$$ show that the predicted rate law is the same as the experimental rate law.

Key Concepts

Rate-Determining Step

The rate-determining step is the slowest step in a multi-step reaction mechanism and therefore controls the overall reaction rate. Since the rate of the overall reaction is effectively governed by this step, its kinetic parameters largely determine the form of the overall rate law. Identifying the rate-determining step is key to understanding how the concentrations of the reacting species influence the rate.

Rate Law

The rate law expresses how the rate of a chemical reaction depends on the concentration of its reactants. It is typically determined experimentally and reveals the order of the reaction with respect to each reactant. In the context of reaction mechanisms, the predicted rate law should be consistent with the experimentally observed one, thus providing insight into the steps that constitute the overall reaction.

Reaction Mechanism

A reaction mechanism is a sequence of elementary steps that describes the molecular events leading from reactants to products. Each step in the mechanism proceeds with its own rate law, and the overall rate law is deduced by considering the contributions of the individual steps. The correctness of a proposed mechanism is often validated by comparing its predicted rate law with the experimental rate law.

Intermediates in Reaction Mechanisms

Intermediates are species formed in one step of a reaction mechanism and consumed in a subsequent step; they do not appear in the overall balanced reaction equation. When deriving the rate law from a mechanism, these intermediates are typically eliminated by expressing their concentrations in terms of the concentrations of the reactants, using assumptions like the steady-state or pre-equilibrium approximations.

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