C8H18(l)+252O2(g)→8CO2(g)+9H2O(g)
Part A
Calculate ΔHrxn for the combustion of octane (C8H18), a
component of gasoline, by using average bond energies.
Express your answer using three significant figures.
ΔHrxn =  5030  kJ/mol 
Part B
Calculate ΔHrxn for the combustion of octane by using
enthalpies of formation from Appendix IIB in the textbook. The
standart enthalpy of formation of C8H18 is 250 kJ/mol.
Express your answer using three significant figures.


ΔHrxn =  kJ/mol 
Part C
What is the percent difference between the two results?
Express your answer using two significant figures.


% 
Part D
Which result would you expect to be more accurate?
the value calculated from the heats of formation  
the value calculated from the average bond energies 
Answer
Part A Hn C9) (g(39 3.st)+1(mti,e)HE2so.+6] t3! 48.oe21て6. 387C250] 346+250 paite percentaitterereo 50T+.tt6Cso 30) =