The Rate & Extent of Chemical Change

• When you strike a match, it causes a tiny amount of red phosphorus to be converted to white phosphorus, which then ignites spontaneously.
• Name four factors that affect the rate of chemical reactions

  • Temperature
  • Concentration and pressure
  • Surface area
  • Catalysts
• Collision theory states that for particles to react, they have to collide with sufficient energy.
• Reactions with a catalyst will have a smaller activation energy.
• Transition metals make good catalysts
• At equilibrium, if the concentration of reactants is higher than products, the position of equilibrium lies to the left.
• If the position of the lies to the right, it means there are more products.
• In a reversible reaction, if the forward reaction is endothermic, what would be the affect of increasing the temperature?

  Equilibrium would shift to the right
• In a reversible reaction, if the forward reaction is exothermic, what would be the effect of decreasing the temperature?

  Yield of products would increase
• Le Chatelier's principle states that if you change the conditions of a reversible reaction, the position of equilibrium will shift to try and counteract the change.
• At the equilibrium, if there are more products than reactants, the position of equilibrium lies to the right.
• What are the three factors that affect the position of equilibrium?

  • Temperature
  • Concentration
  • Pressure
• Negative energy (enthalpy) means the reaction is exothermic
• When products are being made as quickly as reactants, the reaction is said to have reached equilibrium.
• Catalysts speed up the rate of reaction by providing an alternative reaction pathway, which has lower activation energy.