Answer
Energy change = -1276 kJ/mol
Step-by-step explanation
Using the given information, the energy change that occurs during the combustion of ethanol is calculated below.
Energy change = (energy of bonds broken) - (energy of bonds formed)
Energy of bonds broken = 5(C-H) + (C-C)+ (C-O) + (O-H) + 3(O-O)
Energy of bonds broken = 5(413) + 347 + 358 + 467 + 3(495)
Energy of bonds broken = 2065 + 347 + 358 + 467 + 1485 = 4722 kJ/mol
Energy of bonds formed = 4(C=O) + 6(O-H)
Energy of bonds formed = 4(799) + 6(467)
Energy of bonds formed = 3196 + 2802= 5998 kJ/mol
Energy change = (energy of bonds broken) - (energy of bonds formed)
Energy change = 4722 kJ/mol - 5998 kJ
Energy change = -1276 kJ/mol