Rate determining step

• Rate-determining step


  The slowest step in a multi-step reaction sequence
• Multi-step reactions


  Reactions that take place in a series of steps rather than a single step
• An overall chemical equation compares the reactants and products
• Stoichiometry


  The relative amounts of the species in a reaction, given by the balancing numbers
• A reaction can only take place when particles collide
• For a single-step reaction, multiple particles would have to collide simultaneously, which is extremely unlikely
• Reaction mechanism


  The series of steps that make up an overall reaction
• The slowest step in a multi-step reaction sequence is called the rate-determining step
• Predicting reaction mechanisms


  Chemists use their knowledge and understanding of chemical principles

  Propose possible mechanisms for reactions

  Evaluate whether a proposed mechanism is likely to be correct
• Rate equation


  Only includes reacting species involved in the rate-determining step
• The orders in the rate equation match the number of species involved in the rate-determining step
• The rate-determining step provides important evidence in supporting or rejecting a proposed reaction mechanism
• Hydrolysis of haloalkanes


  RX + OH- -> ROH + X-

  Can be investigated experimentally to determine the overall order of reaction, the rate equation, and a possible mechanism