Modeling Complex Chemical Reactions

Mathematically, if A decays to B, GoldSim computes the rate of change of mass (at a particular location) as follows:

dM_A/dt = - M_A λ_A

dM_B/dt = M_A λ_A R_BA W_B / W_A

where:

M_A is the mass of species The chemical (or non-chemical, such as bacterial or viral) constituents that are stored and transported through an environmental system in a contaminant transport model. In GoldSim, the Species element defines all of the contaminant species being simulated (and their properties). A (mass);
dM_A/dt is the rate of change of species A (mass/time);
dM_B/dt is the rate of change of species B (mass/time);
λ_A is the decay rate of species A (1/time);
R_BA is the stoichiometry (moles B produced per moles A decayed);
W_A is the molecular (or atomic) weight of species A; and
W_B is the molecular (or atomic) weight of species B.

These equations are appropriate for first-order decay reactions.

Note: In order to model reactants, you must have the RT Module. If you are using the CT Module, you can model decay, but cannot model any reactants.