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These can be used to calculate the [[energy]] released per [[mole]] in a [[Chemical Reaction|chemical reaction]].
'''Example 1'''
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|[[File:StructuralDiagramMethane+Oxygen.png|center|500px]]
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| style="height:20px; width:200px; text-align:center;" |In the [[Chemical Reaction|reaction]] between [[Methane]] and [[Oxygen]] the [[Chemical Bond|chemical bonds]] in the [[reactant]]s must be broken first before the [[Chemical Bond|bonds]] in the [[product]]s are formed.
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There are 4 C-H [[Chemical Bond|bonds]] and 2 O=O [[Chemical Bond|bonds]].
4 x 413 + 2 x 498 = 2648kJ
Therefore 2648kJ/mol are needed to break the [[Chemical Bond|bonds]] in the [[reactant]]s.
There are 2 C=O [[Chemical Bond|bonds]] and 4 O-H [[Chemical Bond|bonds]].
2 x 799 + 4 x 464 = 3454kJ
Therefore 3454kJ/mol is released when the [[Chemical Bond|bonds]] in the [[product]]s form.
Once the [[Chemical Reaction|reaction]] is complete 806kJ will be released.
'''Example 2'''
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|[[File:StructuralDiagramHydrogen+Nitrogen.png|center|500px]]
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| style="height:20px; width:200px; text-align:center;" |In the [[Chemical Reaction|reaction]] between [[Hydrogen]] and [[Nitrogen]] the [[Chemical Bond|chemical bonds]] in the [[reactant]]s must be broken first before the [[Chemical Bond|bonds]] in the [[product]]s are formed.
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There are 3 H-H [[Chemical Bond|bonds]] and 1 N≡N [[Chemical Bond|bonds]].
3 x 436 + 1 x 941 = 2249kJ
Therefore 2249kJ/mol are needed to break the [[Chemical Bond|bonds]] in the [[reactant]]s.
There are 6 N-H [[Chemical Bond|bonds]].
6 x 391 = 2346kJ
Therefore 2346kJ/mol is released when the [[Chemical Bond|bonds]] in the [[product]]s form.
Once the [[Chemical Reaction|reaction]] is complete 97kJ will be released.