Can you PLEASE help me with CHEM? Using bond energies to determine the enthalpy of reaction for the following reaction???

Question

I am kind of confused with this, so if you could show your work so I understand how you get the answer, I would appreciate it more than you know!!!

Use the Table of Bond Energy Terms (BE), to determine H reaction for the following reaction. Enthalpy of Reaction (H) = H(bond enthalpies of bonds broken) - H(bond enthalpies of bonds formed)

C6H12O6 → 2C2H5OH + 2CO2

There are structural diagrams for this, but I can't put them up here. However, here are the bond energies that I have (I may be missing some, so please let me know)

C-O = 85.5
H-O = 111
C-H = 99
C-C = 83
C=O = 178

 

I thought it might look something like this, but my answer seemed really odd, so I think I did something wrong.. 

[7(CH) + 5(CO) + 1(C=O) + 5(OH)] - [10(CH) + 2(CC) + 2(CO) + 2(OH) + 4(C=O)]

I reduced and got something like -407.5 kJ, but I am very uncertain of how to solve these problems, so I don't think I did it write. 


Thank you SO MUCH for the help!!!

Answer 1

 It seems ok.

Answer 2

Hi Angelica,

 

From what you've written, this looks just fine. Assuming the sugar is in the keto(or aldo) form, you have the proper number of bonds of each type, and in the proper part of your equation. Without doing the math, the final number for the ΔH_rxn is also reasonable.

 

My only suggestion would be to double check your arithmetic, and if that works out, be satisfied that you did this problem correctly!

 

Jim S.