Exothermic and endothermic 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?

  The total energy of reactants and products
• What does a reaction profile show on the y-axis and x-axis?

  Total energy of molecules and progress of reaction
• How are products represented in an exothermic reaction profile?

  Lower down than the reactants
• 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 is an example of an endothermic reaction?

  Breaking down calcium carbonate
• How is energy represented in an endothermic reaction profile?

  Products are higher than reactants
• What is activation energy in a reaction profile?

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

  Higher activation energy requires more energy
• How can activation energy be shown on a reaction profile?

  As the increase in energy from reactants
• What would happen if we increased the activation energy in a reaction profile?

  The curve would go higher
• How would you label a reaction profile for specific chemicals?

  By writing the chemicals from the equations
• What are the characteristics of exothermic reactions?

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

  • Absorb energy from surroundings
  • Require heat to proceed
  • Products have higher energy than reactants
• What are the key components of a reaction profile?

  • Y-axis: Total energy of molecules
  • X-axis: Progress of the reaction
  • Reactants on the left, products on the right
  • Activation energy represented as a curve
• What is the role of heat in chemical reactions?

  • In exothermic reactions: heat is released
  • In endothermic reactions: heat is absorbed
• How does activation energy influence reaction rates?

  • Higher activation energy slows down reactions
  • Lower activation energy speeds up reactions