Chapter 10

• What does the rate of a chemical reaction measure?

  How fast a product is being formed
• How is the rate of a reaction defined?

  Change in concentration over time
• What factors affect the rate of a chemical reaction?

  • Concentration (or pressure for gases)
  • Temperature
  • Use of a catalyst
  • Surface area of solid reactants
• What is an effective collision in a chemical reaction?

  A collision that leads to a chemical reaction

  
• What two conditions make a collision more effective?

  Correct orientation and sufficient energy
• What is the activation energy barrier in a reaction?

  The minimum energy required for a reaction
• What is the significance of surface area in reaction rates?

  It affects the rate of solid reactants
• How does temperature influence the rate of a chemical reaction?

  Higher temperatures generally increase reaction rates
• What role does a catalyst play in a chemical reaction?

  It speeds up the reaction without being consumed
• What is a catalyst?

  A substance that changes reaction rates
• How does a catalyst affect a chemical reaction?

  It changes the rate without permanent change
• What happens to a catalyst at the end of a reaction?

  It is regenerated
• What are homogenous catalysts?

  Catalysts in the same state as reactants
• What are heterogeneous catalysts?

  Catalysts in a different state from reactants
• How do reactants interact with a heterogeneous catalyst?

  They are adsorbed onto the catalyst's surface
• What occurs after the reaction on a catalyst's surface?

  Products leave the surface by desorption
• What states are catalysts typically in?

  Typically solids, with gases or liquids
• What is the advantage of using a catalyst regarding temperature?

  High temperatures are not needed
• How does a catalyst lower activation energy?

  • Provides an alternate pathway for the reaction
  • Lowers the energy barrier for the reaction
• What is the behavior of molecules in a gas, liquid, or solution?

  Some move slowly with low energy, others fast
• What does the Boltzmann distribution describe?

  The distribution of molecular energies in a system

  
• What is the minimum amount of energy needed for a reaction to start called?

  Activation energy
• How does the rate of reaction change with fewer molecules exceeding activation energy?

  Rate decreases due to less frequent collisions

  
• What happens to the rate of reaction as temperature increases?

  More particles exceed activation energy

  
• Why does increasing temperature lead to more collisions?

  More particles have energy greater than activation energy

  
• What role does a catalyst play in a chemical reaction?

  Provides an alternative pathway with lower activation energy

  
• How does a catalyst affect the number of molecules with sufficient energy?

  Increases the number exceeding activation energy

  
• What are the key factors affecting the rate of a chemical reaction?

  • Activation energy
  • Temperature
  • Concentration of reactants
  • Presence of catalysts

  
• What are reversible reactions?

  Reactions that occur in both directions
• What is dynamic equilibrium in a chemical reaction?

  • Rate of forward reaction equals rate of reverse reaction
  • Concentrations of reactants and products remain unchanged
  • Both reactions occur simultaneously

  
• What must be true for a reaction to remain in equilibrium?

  The system must be closed
• What does a closed system do in terms of external influences?

  It isolates temperature, pressure, and concentrations
• What does Le Chatelier's principle state?

  • System readjusts to minimize external changes
  • Position of equilibrium may change with external changes
  • Applies to temperature, pressure, and concentration changes
• What happens to the position of equilibrium when more reactant molecules are added?

  The position shifts to the right

  
• How does changing the concentration of a reactant or product affect equilibrium?

  It changes the rate of forward or reverse reactions

  
• What indicates a shift to the right in an equilibrium system?

  More products are formed than reactants
• What indicates a shift to the left in an equilibrium system?

  More reactants are formed than products

  
• How can the position of equilibrium be illustrated in experiments?

  • Use equilibria with different colors
  • Change concentration of reactants or products
  • Observe shifts in equilibrium position

  
• What happens when conditions of an equilibrium system are changed?

  The position of equilibrium shifts to counteract the change
• What is a dynamic equilibrium?

  When forward and reverse reaction rates are equal