Reaction steps and Activation Energies

[engineer23]

Homework Statement

The overall activation energy E is 60 kcal/mol.
Reaction steps are:
CH3CHO --> .5CH3CO + .5CH3 + .5H2 E1 = 80 kcal/mol
CH3CO --> CH3 + CO E2 = ?
CH3 + CH3CHO --> CH4 + CH3CO E3 = 10 kcal/mol
CH3 + CH3CO --> minor products E4 = 5 kcal/mol

Estimate E2.

Homework Equations

Arrhenius equation k = A exp (-E/RT)

The Attempt at a Solution

Does E1 + E2 + E3 + E4 = E? If so, then E2 = -35 kcal/mol. If this is the case, what does negative activation energy mean (physically)?

Do I need to use the Arrhenius equation and/or d[M]/dt expressions to solve this problem. Since E1 >> E3 and E4, are there any assumptions I can make?

I feel like I'm missing something here.

Thanks!

 

[Stevedye56]

I am almost positive that if you have a negative activation energy that it means that the reaction will take place and that it will not be possible to stop it.

Hope this helps.

Steve