Bond energy

• What is the primary focus of bond energies?

  Energy transfer in chemical reactions
• What must energy do to break bonds?

  Energy must be supplied to break bonds
• What happens to old bonds during a chemical reaction?

  Old bonds are broken and new bonds formed
• What is required to break existing bonds?

  Energy must be supplied
• What occurs when new bonds are formed?

  Energy is released during bond formation
• How does the energy used to break bonds compare to the energy released when forming bonds?

  More energy is used to break bonds than released
• What is the relationship between bond breaking and energy?

  Bond breaking requires energy input
• What is the overall energy change in a reaction?

  Energy change = energy required to break bonds - energy released
• What does a positive energy change indicate?

  Endothermic reaction occurs
• What does a negative energy change indicate?

  Exothermic reaction occurs
• How can bond energies be used in calculations?

  To calculate overall energy change in reactions
• What is the bond energy associated with a specific bond?

  It is the energy required to break that bond
• How does bond energy vary among compounds?

  It varies slightly depending on the compound
• How can known bond energies be used in reactions?

  To calculate energy changes for reactions
• How do you calculate the overall energy change for the reaction?

  Energy change = 678 - 431
• What is the overall energy change for the reaction?

  247 kJ/mol
• Where can you find more information on energy transfer?

  Page 83 of the material