Finite chemistry rate and multiple step
 

Hi all,


i´ve a problem to simulate a chemical process.
In hope to get help i tell it you.

Reaction 1 (Single step): A+B -> C+D
Reaction 2 (Single step): D+B -> C+E
Reaction 3 (Multiple step): Reaction1, Reaction 2

for my material i took reacting mixture -> Reaction 3

the molar ratio of A/B is 1/3...
reaction rate 1 > reaction rate 2...

I expected a curve (for concentration) for D with a maximum at that point where no more A is in the system. After that point the curve should go down..
But i got a curve with a positive acclicity...
I got more and more D although there is no more A...
what i have done wrong...it seems that the reaction are not coupled...but i have no idea what to change...
Do you know the problem/solution and could you help me?

Thanks a lot