rate equations

• rate of reaction

  -change in concentration of a reactant or product per unit time

  found by:

  -measuring decrease in the conc of a reactant over time

  -measuring increase in conc of a product over time
• order of reaction

  -shows how the conc of a reactant affects rate of reaction

  -the power to which the conc of that reactant is raised in the rate equation
• 0 order

  -no effect on the rate of the reaction and therefore not included in the rate equation at all
• 1st order

  -the rate is directly proportional to the conc of that reactant
• 2nd order

  -the rate is directly proportional to the square of the conc of that reactant
• overall order of a reaction

  -sum of the powers of the reactants in a rate equation
• half-life

  time taken for the conc of a limiting reactant to become half of its initial value
• Arrhenius equation

  -shows the relationship between the rate constant, the temperature and the activation energy

  k=Ae^(-Ea/RT)

  k - the rate constant

  A - arrhenius constant

  Ea - activation energy (J mol-1)

  T - temp (K)

  e - mathematical constant
• rate determining step

  -the slowest step in the reaction

  -if reactant appears in the RDS then the conc of that reactant will also appear in the rate equation
• bimolecular reaction

  two species involved in the RDS
• unimolecular reaction

  one species involved in the RDS
• RDS intermediate

  derived from the substances that react together to form it in the RDS