[jena]

Hi,

I understand how to set up the problem, but I'm having problem getting the enthalpy.

The question reads:

What is the enthalpy difference (within 1kcal/mole) for the second propagation step of the reaction of isoheptane, bromine and light going to the major product of this reaction?

My setup

Initiation: Br-Br----> Br₂
Propagation 1: (CH3)₂CHCH₂CH₂CH₃+ Br ----> (CH3)₂CHCH₂CH₂CH₂+ HBr

Propagation 2: (CH3)₂CHCH₂CH₂CH₂+ Br-Br --->(CH3)₂CHCH₂CH₂CH₂Br + Br

So how do I do the bond dissocations for bonds that are greater than the regular ethane bonds that they give in our textbooks.  

Thank you