Aqueous equilibrium reactions are calculated as forward and reverse reactions. The reverse rate constant must be provided as part of the input data and the forward rate constant is calculated using the provided reverse rate constant and an equilibrium constant of the following format:

\[ Ae^{C({1/T-1/298})} \]

where \(A\) is the pre-exponential factor ( \(s^{-1}\)), \(C\) is a constant and \(T\) is the temperature (K).

Input data for aqueous equilibrium equations should take the form :

{
  "type" : "AQUEOUS_EQUILIBRIUM",
  "A" : 123.45,
  "C" : 123.45,
  "k_reverse" : 123.45,
  "phase" : "my aqueous phase",
  "time unit" : "MIN",
  "aqueous-phase water" : "H2O_aq",
  "ion pair" : "spec3-spec4",
  "reactants" : {
    "spec1" : {},
    "spec2" : { "qty" : 2 },
    ...
  },
  "products" : {
    "spec3" : {},
    "spec4" : { "qty" : 0.65 },
    ...
  }
  ...
}

The key-value pairs reactants and products are required. Reactants and products without a qty value are assumed to appear once in the reaction equation. Reactant and product species must be present in the specified phase and include a molecular weight [kg mol-1] parameter in kg \(\mbox{mole}^{-1}\). The parameter aqueous-phase water is required and must be the name of the aerosol-phase species that is used for water. The parameter ion pair is optional. When it is included its value must be the name of an ion pair that is present in the specified aerosol phase. Its mean binary activity coefficient will be applied to the reverse reaction.

When A is not included, it is assumed to be 1.0, when C is not included, it is assumed to be 0.0. The reverse reaction rate constant k_reverse is required.

The unit for time is assumed to be s, but inclusion of the optional key-value pair time unit = MIN can be used to indicate a rate with min as the time unit.