The rate and extent of chemical change

• What is the collision theory in chemistry?

  Reactant particles must collide to react
• What happens when reactant particles collide without enough energy?

  They bounce apart without reacting
• What is the term for the energy needed for a reaction to occur?

  Activation energy
• How does increasing temperature affect reaction rates?

  Particles move faster and collide more
• What effect does increasing concentration have on reaction rates?

  More reactant particles lead to frequent collisions
• How does increasing pressure affect gas reactions?

  Less space means more frequent collisions
• Why does increasing surface area of solids increase reaction rates?

  More surface area exposes more reactant particles
• What is a catalyst?

  A substance that speeds up reactions without being used up in the reaction
• How do catalysts affect activation energy?

  They provide a pathway with lower activation energy
• What is the formula for mean rate of reaction using reactant quantity?

  Mean rate = quantity of reactant used / time taken
• What is the formula for mean rate of reaction using product quantity?

  Mean rate = quantity of product formed / time taken
• How is the rate of reaction calculated when measuring gas production?

  Rate = volume of gas produced / time taken
• What does the rate of reaction indicate?

  How quickly products are formed or reactants used
• What is the unit for rate of reaction involving mass change?

  g/s
• What is the unit for rate of reaction involving volume change?

  cm³/s
• What is activation energy?

  Minimum energy needed for a reaction