Bond energy and activation energy

by sgstudent
Tags: activation, bond, energy
 P: 645 Is the energy required to break the bonds of a compound in order for the reaction to occur (bond energy) the same as activation energy? Thanks for the help!
 Admin P: 23,592 Do you need to break the bonds entirely to reach the transition state?
P: 645
 Quote by Borek Do you need to break the bonds entirely to reach the transition state?
I think so, when we do the calculating it is enthalpy to break bonds+enthalpy to form bonds. When we calculate it the bond breaking part is the bond energy so all the bonds have to break. So
I'm guessing that the
activation energy is the energy required to break the
bonds. But then again, when a substitution reaction only the chlorine gas' and one C-H bond gets broken. So is the activation energy the energy to break only certain bonds?Thanks!

 Admin P: 23,592 Bond energy and activation energy What is a transition state?
P: 645
 Quote by Borek What is a transition state?
from what I read I think its the intermediate part of the reaction meaning its the reactants st the peak of the activation energy 'mountain'. So not all the bonds are broken? Because in the reactions I see are pike H2+O2-->2H2O so the transition state all the bonds are broken. But when I see my sister's O level notes there are questions with organic reactions so I don't thing its possible for all the bonds to break. But she still calculated it such that all the bonds are broken so I'm white confused here... thanks for tbe help!
Emeritus
PF Gold
P: 11,155
 Quote by sgstudent I think so, when we do the calculating it is enthalpy to break bonds+enthalpy to form bonds.
I think you are picturing a process like this:

reactants --> (bond breaking) --> transition state = individual species with all relevant bonds broken --> (bond formation) --> products

But does it have to follow that sequence?
P: 645
 Quote by Gokul43201 I think you are picturing a process like this: reactants --> (bond breaking) --> transition state = individual species with all relevant bonds broken --> (bond formation) --> products But does it have to follow that sequence?
I'm guessing that not all the bonds have to break since in some reaction only certain bonds are required to be broken like in the CH4+Cl2 case. But then the part that scares me is on finding the activation energy since when such reaction occurs only the involved bonds are the activation energy. Is there a way to determine it? When I draw out the full structural formula it gives some insights but still its quite difficult...thanks for the help guys!