What is the Difference Between Elementary Step and Rate Determining Step?

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The difference between an elementary step and a rate-determining step lies in their roles within a chemical reaction mechanism.

  • Elementary step: An elementary step is a single, basic reaction step within a multistep reaction process, which involves the formation or consumption of one or more chemical species. These steps have different rates, and an elementary step can be either fast or slow.
  • Rate-determining step: The rate-determining step is the slowest step within a chemical reaction mechanism, and it limits the overall rate of the reaction. This step determines the rate law for the overall reaction, as it is the slowest step that determines the speed at which the reaction proceeds.

In summary, an elementary step is a single reaction step within a multistep process, while the rate-determining step is the slowest step in a chemical reaction mechanism that determines the overall rate of the reaction.

Comparative Table: Elementary Step vs Rate Determining Step

The main difference between an elementary step and a rate-determining step lies in their speed and impact on the overall reaction rate. Here is a comparison table highlighting the differences:

Feature Elementary Step Rate-Determining Step
Definition An elementary step is an individual reaction in a proposed reaction mechanism. The rate-determining step is the slowest step in a multistep reaction mechanism, which determines the overall reaction rate.
Speed Can be fast or slow. Always the slowest step among the series of steps.
Reaction Rate Does not necessarily limit the overall reaction rate. Limits the overall reaction rate, as the reaction cannot proceed faster than its slowest step.

In summary, an elementary step is an individual reaction within a reaction mechanism, while the rate-determining step is the slowest step in a multistep reaction mechanism, which controls the overall reaction rate.