Rate-Determining Step

Definition

The rate-determining step is the slowest elementary step in a reaction mechanism that controls the overall rate of the chemical reaction. It is the step that limits the speed at which the reaction can proceed and is the crucial factor in determining the reaction rate.

5 Must Know Facts For Your Next Test

1. The rate-determining step is the slowest step in a reaction mechanism and controls the overall rate of the reaction.
2. Identifying the rate-determining step is crucial for understanding and predicting the behavior of a chemical reaction.
3. The rate-determining step often involves the breaking of a strong chemical bond or the formation of a high-energy intermediate.
4. Factors that can affect the rate-determining step include temperature, pressure, and the concentrations of reactants.
5. Knowing the rate-determining step can help chemists optimize reaction conditions to increase the rate of a desired reaction.

Review Questions

• Explain how the rate-determining step relates to the overall reaction rate in the context of 12.2 Factors Affecting Reaction Rates.
  • The rate-determining step is the slowest elementary step in a reaction mechanism and is the crucial factor that controls the overall rate of the chemical reaction. According to 12.2 Factors Affecting Reaction Rates, the rate-determining step is the step that limits the speed at which the reaction can proceed. By identifying the rate-determining step, chemists can understand which factors, such as temperature, pressure, or reactant concentrations, will have the greatest impact on the overall reaction rate and can optimize those factors to increase the rate of the desired reaction.
• Describe how the rate-determining step is used to determine the rate law in the context of 12.3 Rate Laws.
  • The rate-determining step is a crucial concept in 12.3 Rate Laws, as it is used to determine the rate law for a chemical reaction. The rate law describes the relationship between the reaction rate and the concentrations of the reactants. By identifying the rate-determining step, which is the slowest step in the reaction mechanism, chemists can determine the order of the reaction with respect to each reactant and formulate the appropriate rate law equation. The rate-determining step, and the associated rate law, are essential for predicting and understanding the kinetic behavior of a chemical reaction.
• Analyze how the identification of the rate-determining step can provide insights into the reaction mechanism in the context of 12.6 Reaction Mechanisms.
  • In the context of 12.6 Reaction Mechanisms, the rate-determining step is a crucial piece of information that can provide valuable insights into the overall reaction mechanism. By determining the rate-determining step, which is the slowest elementary step in the mechanism, chemists can infer the nature of the intermediate species, the order of the steps, and the relative rates of the individual steps. This knowledge can then be used to propose a plausible reaction mechanism that is consistent with the experimental observations, such as the rate law and the effects of various factors on the reaction rate. The identification of the rate-determining step is, therefore, a powerful tool for elucidating the complex series of events that occur during a chemical reaction.

Related terms

Reaction Mechanism: A reaction mechanism is a step-by-step description of the elementary steps that occur during a chemical reaction, showing the rearrangement of atoms and the formation of intermediates.

Elementary Step: An elementary step is the simplest possible chemical reaction that occurs as part of a more complex reaction mechanism, involving the breaking and/or formation of one or more chemical bonds.

Reaction Kinetics: Reaction kinetics is the study of the rates of chemical reactions and the factors that influence those rates, such as temperature, pressure, and the concentrations of reactants.