1.5 Kinetics

• According to collision theory, when do chemical reactions occur?

  When particles of substances collide
• For a chemical reaction to occur successfully, what two conditions must be met during a collision?

  Sufficient energy and correct particle orientation
• What term describes the minimum energy required for a reaction to occur?

  Activation energy
• How do reaction conditions influence the likelihood of successful collisions?

  By impacting the energy of the particles
• How can reaction conditions be altered to increase the reaction rate?

  To provide particles with more energy
• What is the name of the distribution pattern of molecular energies in a substance?

  Maxwell-Boltzmann distribution

  
• What happens to the shape of the Maxwell-Boltzmann curve when reaction conditions change?

  The shape of the curve alters
• What does the total area under the Maxwell-Boltzmann curve represent?

  The total number of molecules
• Why does the area under the Maxwell-Boltzmann curve remain constant?

  Because the total number of molecules remains constant

  
• What form of energy is transferred to a substance when it is heated?

  Thermal energy
• What does thermal energy convert into when a substance is heated?

  Kinetic energy
• How does increased movement of molecules affect collisions?

  Collisions occur more often and energetically
• How does increasing the reaction temperature affect the rate of reaction?

  Increases the rate of reaction
• How does the Maxwell-Boltzmann distribution change at an increased temperature?

  Shifts to the right
• How does increasing the concentration of a sample affect the arrangement of molecules?

  Molecules are packed closer together
• How does increasing concentration affect the likelihood of collisions and the reaction rate?

  More collisions, reaction rate increases
• How does increasing pressure affect the arrangement of molecules?

  Molecules are packed closer together
• What happens to the Maxwell-Boltzmann distribution when pressure is increased?

  The distribution is shifted to the right
• What is a catalyst?

  Increases reaction rate without being used
• How does a catalyst increase the rate of reaction?

  By lowering the activation energy
• How does a catalyst affect the Maxwell-Boltzmann distribution curve?

  It remains unchanged in shape

  
• How does the presence of a catalyst affect the position of the activation energy on the Maxwell-Boltzmann distribution?

  Shifted to the left

  
• What impact does shifting the activation energy to the left have on the proportion of molecules with sufficient energy to react?

  Greater proportion
• Why can reaction conditions be changed?

  To increase rate
• What effect does increasing temperature have on the energy of collisions?

  Collisions with greater energy
• Why does increasing the concentration increase reaction rate?

  Collisions become more likely
• How is increasing pressure similar to increasing concentration?

  Molecules packed closer together
• What does a catalyst provide for a chemical reaction?

  An alternative reaction path