This model represents a generic 2-stage chemical reaction. The mechanics of a chemical reaction are most commonly modeled by an agent model, to clearly delineate the reactions between the molecules, but the relative quantities of reactants and products over time are often modeled with systems models.
There are three compounds in this chemical reaction - the reactant, an intermediate compound, and the product. As the model progresses, reactants change into intermediaries, which then change to products.
This model is very simple. After setting the parameters for rates of transformation between the stages, click run to simulate the reaction.
In this case, there is no "reverse reaction" so the reaction will go to completion. The rate of this completion will depend on the parameters set.