Chemistry 2.5

• Rate of reaction


  The amount of product formed in a certain period of time
• Measuring rate of reaction


  • Measuring the volume of gas given off by a reaction
  • Measuring the loss of a reactant over time when a gas is produced
  • Measuring the rate of using the reactants/time for products to form
• Rate of reaction equation

  Rate = Amount of product formed / Time taken
• Reaction 1: Calcium carbonate and hydrochloric acid


  Calcium carbonate + Hydrochloric acid → Calcium chloride solution + Carbon dioxide + Water
• Best way to measure rate of Reaction 1

  Rate in which the carbon dioxide gas is being released
• Reaction 2: Sodium thiosulfate and hydrochloric acid

  Sodium thiosulfate + Hydrochloric acid → Sodium chloride + Sulfur dioxide + Sulfur + Water
• Best way to measure rate of Reaction 2

  Rate in which the substance changes into a cloudy precipitate (yellow colouring)
• Collision theory


  For a chemical reaction to occur, the reactant particles must collide with each other with enough energy
• Successful collisions


  Collisions where reactants smash into one another, breaking their original bonds to form new bonds with other reactants, making a new substance
• Unsuccessful collisions


  Collisions that do not result in a chemical reaction
• Increasing reaction rate


  Increasing temperature, concentration, surface area, pressure
• Catalyst


  A substance that increases the rate of reaction, without being changed or used up because of the reaction
• Catalysts


  • They lower the activation energy by providing an alternative route for the reaction
  • They aren't found in the chemical equation
• Examples of catalysts


  • Iron in the Haber process for ammonia
  • Platinum and palladium in catalytic converters
  • Enzymes in biological systems