Two solutes, A and B, reversibly react to form C. A + B <---> C reaches equilibrium at the ratio A*B/C = Kd.

Description

   Pseudo-equilibria are often assumed in reaction processes,
and if efficient to compute, can save much computation time
and avoid using the on- and off- rate constants of the reaction. 
This is interesting since the "ratio" A*B/C progresses with time
becoming Kd if t.max is long enough, while the implicit solution 
gives ratio = Kd immediately.

The implicit solution solves

 Mass conservation from initial concentrations
 Definition of chemical equilibrium
 Change from initial concentrations same for ssA and ssB
 
and fails to be compiled if any one of the three equations is omitted.

Comparison of Ordinary Differential Equation model with implicit and analytic solutions.

Equations

The equations for this model may be viewed by running the JSim model applet and clicking on the Source tab at the bottom left of JSim's Run Time graphical user interface. The equations are written in JSim's Mathematical Modeling Language (MML). See the Introduction to MML and the MML Reference Manual. Additional documentation for MML can be found by using the search option at the Physiome home page.