How do I add the reaction kinetics law for a pseudo-first order rate reaction?

I am creating a model of a reaction of two species. The reaction is pseudo-first order rate reaction. The reaction is as follows:

A + B -> P

Reaction Rate should be:

k*A

(B is not involved in reaction rate calculation, as it is added in excess.)

How do I add the reaction kinetics law for a pseudo-first order rate reaction? It does not seem I could use "MassAction" option.

Answer 1

[Rick Paxson]

Hi,

The way to do this is to directly specify the reaction rate for the reaction rather than specifying a kinetic law. That is if you want k*A to be the rate.

If you have the case where the concentration of B remains constant but participates in the reaction rate you can specify that by setting B to be a boundary condition. Doing this (and specifying Mass Action as the kinetic law) will result in a reaction rate of K*B*A but B will be constant. (i.e. k' = K*B) and the reaction rate will be k'*A. Let me know if this answers your question.