R&E of chemical change

• Mean rate of reaction is:

  Amount of reactant used OR product formed/time taken
• If measuring the amount of reactants used, the units may then be given as...

  g/s
• If measuring the amount of products formed, the units may then be given as...

  cm^3/s
• If measuring the time it takes for a reaction mixture to change colour, the units may then be given as...

  1/time taken for solution to change colour
• The minimum amount of energy required to cause a reaction is called the...

  Activation energy
• Factors surrounding activation energy:

  • Temperature
  • Concentration
  • Surface area
• To work out the gradient, you do...


  Difference in the amount of product formed OR reactant used/time
• Chemical reactions only occur when reacting particles collide with each other with sufficient energy
• A catalyst is a substance that increases the rate of a chemical reaction without it being used up in the process
• A catalyst...

  • Reduces the amount of energy needed for a successful collision
  • Makes more collisions successful
  • Speeds up the reaction
  • Provides a surface for the molecules to attach to, which increases their chances of bumping into each other.
• In a closed system...

  no reactants are added and no products are removed