CHEMICAL KINETICS

• Learning Objectives


  • Describe how various factors influence the rate of a reaction
  • Explain reactions qualitatively in terms of molecular collisions
  • Identify the order of reactions
• Adding heat


  Increases the rate of reaction
• Removing heat


  Decreases the rate of reaction
• Adding a catalyst


  Increases the rate of reaction
• Diluting a solution


  Decreases the rate of reaction
• Decreasing the surface area

  Decreases the rate of reaction
• Increasing the concentration


  Increases the rate of reaction
• Breaking a reactant down into smaller pieces

  Increases the rate of reaction
• Colligative properties


  Properties dependent on the number of solute particles dissolved in a given quantity of solvent
• Examples of colligative properties


  • Boiling point
  • Freezing point
• Factors affecting the rate of reaction

  • Nature of reactants
  • Concentration of reactants
  • Temperature
  • Surface area
  • Presence of a catalyst
• Collision theory


  • For a chemical reaction to occur, the reacting particles must collide with one another
  • Reacting particles often collided without reacting
  • For collision to be successful, reacting particles must collide with sufficient energy and proper orientation
• Raising the reaction temperature by 10 ⁰C can double or triple the reaction rate
• The reaction rate decreases with a decrease in temperature
• When solids and liquids react, increasing the surface area of the solid will increase the reaction rate
• Catalysts can lower the activation energy and increase the reaction rate without being consumed in the reaction
• Reaction rate laws


  Express the mathematical relationship between the rate of reaction and concentration of reactants
• Example experiment #1


  • Rate = K [A]^1 [B]^2
• Example experiment #2


  • Rate = K [F2]^1 [ClO2]^1