Endothermic & Exothermic Reactions

• How can exothermic and endothermic reactions be represented?

  Using reaction profiles
• What is the importance of activation energy?

  It is the minimum energy needed for reactions
• What do different chemicals store in their bonds?

  Different amounts of energy
• In the reaction of methane and oxygen, what is compared to determine energy changes?

  The total energy of reactants and products
• How do the energy levels of products compare to reactants in an exothermic reaction?

  Products have less energy than reactants
• What does a reaction profile's y-axis represent?

  Total energy of the molecules
• What does a reaction profile's x-axis represent?

  Progress of the reaction
• What happens to energy in an exothermic reaction?

  Energy is released to the surroundings
• What is the most common type of exothermic reaction?

  Combustion reactions
• What must be supplied to break down calcium carbonate?

  Heat energy
• How do the energy levels of products compare to reactants in an endothermic reaction?

  Products have more energy than reactants
• What is the difference labeled on the reaction profile for an endothermic reaction?

  Energy absorbed
• What does activation energy represent in a reaction profile?

  The minimum energy needed for reactants to collide
• How does the activation energy affect the reaction rate?

  Higher activation energy requires more energy to start
• How can activation energy be represented on a reaction profile?

  As the energy change from reactants to peak
• How would you show a reaction with higher activation energy on a profile?

  Make the curve go higher
• How would you show a reaction with lower activation energy on a profile?

  Make the curve go lower
• What can be labeled on a reaction profile instead of just reactants and products?

  The specific chemicals from the equations
• What are the characteristics of exothermic reactions?

  • Release energy to surroundings
  • Commonly involve combustion
  • Heat energy is a byproduct
• What are the characteristics of endothermic reactions?

  • Absorb energy from surroundings
  • Require heat to proceed
  • Products have higher energy than reactants
• What is the significance of reaction profiles in chemistry?

  • Visual representation of energy changes
  • Helps understand exothermic and endothermic reactions
  • Illustrates activation energy requirements