Exo and Endo

• Endothermic Reactions


  Absorb energy from surroundings
• Endothermic Reactions


  • Ice Packs: Absorb heat, making them cold
  • Photosynthesis: Plants use sunlight to make glucose
  • Thermal Decomposition: Substances break down with heat (e.g., calcium carbonate to calcium oxide and carbon dioxide)
• Endothermic Reaction Profile


  1. Reactants

  2. Activation Energy

  3. Energy Absorbed

  4. Products

  5. Energy Level of Reactants

  6. Energy Level of Products
• Exothermic Reactions


  Release energy to surroundings
• Exothermic Reactions


  • Hand Warmers: Release heat, warming up
  • Combustion: Burning fuels releases heat
  • Respiration: Cells release energy from glucose
• Exothermic Reaction Profile


  1. Reactants

  2. Activation Energy

  3. Energy Released

  4. Products

  5. Energy Level of Reactants

  6. Energy Level of Products
• Bond Energy Calculations


  1. Write structural formulas

  2. Assign bond energies from a given table

  3. Calculate total energy of reactants

  4. Calculate total energy of products

  5. Subtract product energy from reactant energy
• Negative value


  Exothermic
• Positive value


  Endothermic
• What is the term for energy stored in an object due to its position?

  Potential Energy
• What is the energy required to start a reaction called?

  Activation energy
• What do reactants refer to in a chemical reaction?

  Substances that undergo change
• What happens to energy during an exothermic reaction?

  Energy is released
• What do products refer to in a chemical reaction?

  Substances formed after the reaction
• What characterizes the progress of an exothermic reaction?

  Energy is released as the reaction proceeds
• What happens to energy during an endothermic reaction?

  Energy is absorbed
• How do exothermic and endothermic reactions differ in terms of energy flow?

  Exothermic releases energy, endothermic absorbs energy
• What are the key differences between exothermic and endothermic reactions?

  • Exothermic reactions:
  • Release energy
  • Reactants have higher potential energy than products
  • Endothermic reactions:
  • Absorb energy
  • Products have higher potential energy than reactants