What is the difference between a fast step and a slow step in a reaction?

In a chemical reaction, the difference between fast and slow steps relates to how quickly each elementary step occurs:

1. Fast step:
   • Occurs quickly.
   • Usually does not limit the overall reaction rate.
   • Often reaches equilibrium quickly.
2. Slow step (rate-determining step):
   • The slowest step in a multi-step reaction.
   • Controls the overall reaction rate because the reaction can’t go faster than this step.
   • Often has the highest activation energy.

In short:

• Fast steps: quick, don’t limit the reaction.
• Slow step: slow, determines how fast the overall reaction proceeds.