8.57

[siannehazel1B]

How do we know when we are supposed to write out the equations and use a Hess' law approach to solve for the reaction enthalpy? For this problem, i thought we were supposed to use the difference of sums approach because i didn't initially know how to write the combustion reactions

[Shawn Patel 1I]

Hey,
For this question, you would know to find the equations of combustion because the given enthalpies are of combustion. So you would find the combustion reactions, then balance those, and then you could use Hess's Law to find the final reaction enthalpy.