rate determining step

• The slowest step in a reaction mechanism is called the rate determining step, or RDS
• We can use reaction mechanisms, alongside information about what step is the slowest to find the rate equation for a reaction. 
• 1. The rate equation only contains reactants (and occasionally catalysts) which appear before or during the rate determining step
  2. The number of times each reactant appear before or during the rate determining step determines their order
• Making rate equation from reaction mechanism and slowest step

  1. Look for slowest step
  2. Cross out intermediates
  3. Write reactant molecules involved before and during slowest step
  4. Add to rate equation and simplify
• Reactants involved before or during RDS are in the rate equation
• Order of reactants = no. times involved before or during RDS
• If we know reaction mechanism or rate equation we can deduce the RDS