Calculation of enthalpy changes of reaction using bond energies
2 marks · NormalState the meaning of the term 'bond energy' and give the unit in which it is measured.
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Bond energy is the energy needed to break 1 mole of covalent bonds in gaseous molecules; measured in kJ/mol.
Also accept: The energy required to break one mole of covalent bonds in gaseous molecules; measured in kJ/mol; Energy required to break 1 mole of bonds in gaseous molecules; unit: kJ/mol
Common mistakes: Confusing with energy for ionic bonds; Giving wrong unit
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Marking points
B1 · 1 mark · Correct definition of bond energy as energy to break 1 mole of covalent bonds in gaseous molecules.
B2 · 1 mark · Correct unit given as kJ/mol or kilojoules per mole.
Worked solution
Bond energy is the energy needed to break one mole of covalent bonds in gaseous molecules. It is measured in kJ/mol (kilojoules per mole).