energy transfer in reactions

• What instrument is used to measure changes in heat content?

  Thermometer
• What does the law of conservation of energy state?

  Energy cannot be created or destroyed, only transferred
• What happens to energy during chemical reactions according to the law of conservation of energy?

  The overall amount of energy does not change
• If energy is transferred to the surroundings during a chemical reaction, what can be said about the energy of the products compared to the reactants?

  The products have less energy than the reactants
• How does the energy of products relate to the energy of reactants in a chemical reaction where energy is transferred to the surroundings?

  The difference in energy is equal to the amount of energy transferred
• exothermic reaction diagram


  Diagram showing the transfer of heat energy outwards from an exothermic reaction

  
• What is an endothermic reaction?

  An endothermic reaction is a reaction that takes in heat energy.
• What happens to the temperature during an endothermic reaction?

  The temperature decreases during an endothermic reaction.
• What are some typical examples of endothermic reactions?

  • Electrolysis
  • Thermal decomposition reactions
  • First stages of photosynthesis
  • Reaction between citric acid and sodium hydrogencarbonate
• How are cold packs used in sports injury treatment related to endothermic reactions?

  Cold packs use endothermic reactions to take heat away from an injured area to prevent swelling.
• Why is it beneficial to use cold packs based on endothermic reactions for treating sports injuries?

  It prevents swelling by taking heat away from the injured area.
• Endothermic reaction diagram

  Diagram showing the transfer of heat energy from the surroundings into an endothermic reaction

  
• What are the two types of chemical reactions discussed?

  Exothermic and endothermic reactions
• How can changes in heat content be measured?

  With a thermometer
• What does the conservation of energy in reactions imply?

  Energy cannot be created or destroyed, only transferred
• What happens to the energy of products compared to reactants in an exothermic reaction?

  The products have less energy than the reactants by the amount transferred to the surroundings
• What is the significance of energy transfer during a chemical reaction?

  It indicates that energy is conserved and affects the energy levels of reactants and products
• What is an exothermic reaction?

  transfers energy to the surroundings so the temperature of the surroundings increase
• What is an endothermic reaction?

  A reaction that absorbs energy from the surroundings
• exothermic reactions include:


  • combustion
  • oxidation reactions
  • neutralisation
• everyday uses of exothermic reaction:


  • self heating cans
  • hand warmers
• What type of reaction always gives energy out?

  Neutralisation reactions
• What is the energy change in displacement reactions?

  They can either take energy in or give it out
• What type of reaction always gives energy out?

  Combustion reactions
• What happens to the temperature of the surroundings in exothermic reactions?

  • The temperature of the surroundings increases
  • The heat content of the system falls
• What happens to the temperature of the surroundings in endothermic reactions?

  • The temperature of the surroundings falls
  • The heat content of the system increases
• How do exothermic and endothermic reactions differ in terms of heat content and temperature changes?

  Exothermic reactions increase surroundings' temperature and decrease system's heat content, while endothermic reactions decrease surroundings' temperature and increase system's heat content