Exothermic and Endothermic Reactions

• What is meant by an exothermic reaction?

  It transfers energy to the surroundings
• What happens to the temperature of surroundings during an exothermic reaction?

  The temperature increases
• How do scientists represent energy changes in reactions?

  By drawing energy profile diagrams
• What does an energy profile diagram for an exothermic reaction show?

  Products have less energy than reactants
• What does the difference in energy between reactants and products indicate in an exothermic reaction?

  The energy released to the surroundings
• What are two uses of exothermic reactions?

  Hand-warmers and self-heating cans
• What is an endothermic reaction?

  It takes in energy from the surroundings
• What happens to the temperature of surroundings during an endothermic reaction?

  The temperature decreases
• What does an energy profile diagram for an endothermic reaction show?

  Products have more energy than reactants
• What does the difference in energy between reactants and products indicate in an endothermic reaction?

  The energy taken in by the reaction
• What is common between the energy profiles of exothermic and endothermic reactions?

  Both have a peak called activation energy
• What is activation energy?

  The minimum energy for particles to react
• How is activation energy represented on an energy profile diagram?

  From reactants to the peak of the curve
• How can you identify activation energy on an exothermic energy profile?

  It is the energy from reactants to peak
• How can you identify activation energy on an endothermic energy profile?

  It is the energy from reactants to peak
• What are the key characteristics of exothermic reactions?

  • Transfer energy to surroundings
  • Temperature of surroundings increases
  • Examples: combustion, oxidation, neutralization
• What are the key characteristics of endothermic reactions?

  • Take in energy from surroundings
  • Temperature of surroundings decreases
  • Example: thermal decomposition
• What is the significance of energy profile diagrams?

  • Visual representation of energy changes
  • Shows energy levels of reactants and products
  • Indicates activation energy
• What is the role of activation energy in chemical reactions?

  • Minimum energy required for reactions
  • Particles must collide with sufficient energy