7.2.2 Energy Level Diagrams

• What is the energy level comparison in endothermic reactions?

  • Reactants: Lower energy
  • Products: Higher energy
  • Heat: Absorbed
  • Temperature: Decreases
• What happens to the temperature during endothermic reactions?

  The temperature decreases
• How is the energy absorbed by the system represented in the energy level diagram for endothermic reactions?

  It is shown below the energy level line
• How can the energy changes in endothermic and exothermic reactions be used to determine the direction of the reaction?

  • If the energy of the products is higher than the energy of the reactants, the reaction is endothermic and the direction of the reaction is from left to right.
  • If the energy of the products is lower than the energy of the reactants, the reaction is exothermic and the direction of the reaction is from right to left.
• What happens to the temperature during exothermic reactions?

  It increases
• What happens after the activation energy barrier is overcome in exothermic reactions?

  Energy is released as products form
• What is the effect of heat absorption in endothermic reactions?

  It causes the temperature to decrease
• What is the relationship between activation energy and the transition state?

  • Activation energy is the minimum energy required to reach the transition state
  • The transition state is the highest energy point along the reaction pathway
• What do exothermic reactions release to their surroundings?

  Heat
• Where do the final products end up in terms of energy level in an endothermic reaction?

  At a higher energy level than starting point
• What are the key features of the energy level diagram for endothermic reactions?

  • Energy increases from left to right
  • Activation energy peak is higher
  • Energy absorbed by the system is shown below
• How do the energy levels of reactants compare to products in endothermic reactions?

  Reactants have lower energy than products
• What is the relationship between the direction of reaction and the energy changes in endothermic and exothermic reactions?

  • In endothermic reactions, the direction of the reaction is from left to right, with the energy of the products being higher than the energy of the reactants.
  • In exothermic reactions, the direction of the reaction is from right to left, with the energy of the products being lower than the energy of the reactants.
• What is the name of the energy shown in the graph?

  Activation energy
• What is enthalpy change (ΔH)?

  Heat energy released or absorbed during a reaction
• What is the transition state in a chemical reaction?

  It is the highest energy point during a reaction
• How can the energy changes in endothermic and exothermic reactions be used to determine the direction of the reaction?

  • If the energy of the products is higher than the energy of the reactants, the reaction is endothermic and the direction of the reaction is from left to right.
  • If the energy of the products is lower than the energy of the reactants, the reaction is exothermic and the direction of the reaction is from right to left.
• What does activation energy represent in a chemical reaction?

  It is an energy barrier for reactants
• What is the direction of the reaction in an exothermic process?

  From right to left
• How does the activation energy relate to the rate of a chemical reaction?

  • Higher activation energy leads to slower reaction rates
  • Lower activation energy leads to faster reaction rates
  • Catalysts lower the activation energy, increasing the reaction rate
• What are the key features of energy level diagrams for exothermic reactions?

  • Reactants have higher energy than products
  • Peak represents activation energy barrier
  • Energy is released after overcoming the barrier
• What does the energy level diagram illustrate about energy absorption during an endothermic reaction?

  Energy is absorbed throughout the reaction
• What is the relationship between activation energy and the transition state?

  • Activation energy is the energy needed to reach the transition state.
  • The transition state is the highest energy point in the reaction.
  • Reactants must overcome this energy barrier to form products.
• What must reactants do to transform into products in a chemical reaction?

  Overcome the activation energy barrier
• What is the definition of activation energy?

  Minimum energy needed for a reaction to start
• What characterizes exothermic reactions in terms of ΔH?

  They have negative ΔH because they release energy
• What is the relationship between heat absorption and energy levels in endothermic reactions?

  Heat absorption increases the energy level of products
• What are the energy changes in exothermic reactions?

  • Reactants have higher energy than products
  • Heat is released
  • Temperature increases
• What are the key differences between exothermic and endothermic reactions?

  • Exothermic Reactions:
  • Negative ΔH
  • Releases energy
  • Reactants have higher energy than products

  
  

  • Endothermic Reactions:
  • Positive ΔH
  • Absorbs energy
  • Reactants have lower energy than products
• What does the peak in the energy level diagram represent?

  Activation energy barrier
• What is the direction of the reaction in an endothermic process?

  From left to right
• What is the difference between an endothermic and exothermic reaction?

  • Endothermic reactions absorb energy, while exothermic reactions release energy.
  • The energy of the products is higher than the energy of the reactants in endothermic reactions, while the opposite is true for exothermic reactions.
• What does the energy level diagram for exothermic reactions illustrate?

  Energy of reactants is higher than products
• What do endothermic reactions do to heat?

  They absorb heat from their surroundings
• How do energy levels change in exothermic reactions?

  • Energy Level: Reactants (Higher) → Products (Lower)
  • Heat: Absorbed (Reactants) → Released (Products)
  • Temperature: Decreases (Reactants) → Increases (Products)
• What is the energy transfer in exothermic and endothermic reactions?

  • Exothermic: Releases energy
  • Endothermic: Absorbs energy
• What is the difference between an endothermic and exothermic reaction?

  • Endothermic reactions absorb energy, while exothermic reactions release energy.
  • The energy of the products is higher than the energy of the reactants in endothermic reactions, while the opposite is true for exothermic reactions.
• Why is the energy of the products higher than the energy of the reactants in an endothermic reaction?

  Because the reaction absorbs energy from the surroundings
• What is the direction of the reaction in an endothermic process?

  From left to right
• How do the energy profiles of endothermic and exothermic reactions differ in terms of activation energy and energy of products?

  • In endothermic reactions, the activation energy is higher than the energy of the products, while in exothermic reactions, the activation energy is lower than the energy of the products.
  • The energy of the products is higher than the energy of the reactants in endothermic reactions, while the opposite is true for exothermic reactions.