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    Why is it that in when calculating the enthalpy of combustion you use 'bond enthalpies of REACTANTS - bond enthalpies of PRODUCTS'

    but in calculating the enthalpy change of formation you use 'bond enthalpies of PRODUCTS - bond enthalpies of REACTANTS'?

    (the other way round)

    thanks sm
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    (Original post by greys-anatomy)
    Why is it that in when calculating the enthalpy of combustion you use 'bond enthalpies of REACTANTS - bond enthalpies of PRODUCTS'

    but in calculating the enthalpy change of formation you use 'bond enthalpies of PRODUCTS - bond enthalpies of REACTANTS'?

    (the other way round)

    thanks sm
    in formationit is products - reaction and reverse on the combustion because of the negative sign
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    (Original post by greys-anatomy)
    Why is it that in when calculating the enthalpy of combustion you use 'bond enthalpies of REACTANTS - bond enthalpies of PRODUCTS'

    but in calculating the enthalpy change of formation you use 'bond enthalpies of PRODUCTS - bond enthalpies of REACTANTS'?

    (the other way round)

    thanks sm
    doing past papers i wondered this sooo muchh it confused me
 
 
 
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