Given bond energies O-H 463kJ,C-H 413kJ,C-O 360kJ,C-C 348kJ,Calc heat of formation of ethyl alcohol from....?

Given the following bond energies O - H 463kJ, C - H 413kJ, C - O 360kJ, C - C 348kJ, Calculate the heat of formation of ethyl alcohol from the monoatomic gaseous elements. Hence calculate the heat of formation of ethyl alcohol from the elements in theirs standard states. The heats of atomization of C, H and O are 713, 432 and 495kJ respectively.

Given bond energies O-H 463kJ,C-H 413kJ,C-O 360kJ,C-C 348kJ,Calc heat of formation of ethyl alcohol from....?
If the reactants are the elements in their standard states, then the equation looks like this:





2 C + 3 H2 + 1/2 O2 ==%26gt; CH3CH2OH





The part about "monoatomic gaseous elements" has me confused, since H2 and O2 are diatomic in their standard states.





Nevertheless, you are forming the following bonds





5 C-H bonds (5 x 413)





1 C-C bond (348)





1 C-O bond (360)





1 H-O bond (463)





Grand total of energy released = 3236 kJ





Go back to the original equation:





2 C + 3 H2 + 1/2 O2 ==%26gt; CH3CH2OH





713 kJ is required to atomize carbon (713 x 2)


432 kJ is required to break the H-H bond (432 x 3)


495 kJ is required to break the O=O bond (495 x 1/2)





Grand total of energy absorbed = 2970 kJ


Grand total of energy released = 3236 kJ





Overall energy change = -266 kJ





Hope that's right!

rosemary