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Help understanding bond energy

  1. Aug 5, 2016 #1
    I'm having trouble understanding the definition of bond energy. My textbook defines it as the energy required to break 1 mole of the bond in the gas phase. I don't understand what it means to break 1 mole of a bond.
    Cl2 (g) ---> 2 Cl(g) Bond energy = 243 kJ.
    Since 1 mole of Cl2 is 1.2*1024 molecules, does this mean bond energy is the total energy required to break 1.2*1024 Cl-Cl bonds?
  2. jcsd
  3. Aug 5, 2016 #2


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    One mole of Cl2 is 6.02x1023 molecules of Cl2. There are 1.2x1024 Cl atoms, but only 6.02x1023 Cl-Cl bonds. So the bond energy is the total energy required to break 6.02x1023 Cl-Cl bonds.
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