Two Calculation Pathways

Once the input water is given, there are two principal ways to proceed:

button Start: interpretation & check of a water sample (CBE, calcite saturation, etc.)
button Reac: addition of 1 to 4 chemicals (acids, bases, salts)

In case of reactions you can also start from pure water (button H2O), which then mimics a pH calculator (cf. online demo).

The two calculation paths starting from the input water to the final solutions (Output 1, Output 2) can be summerized as follows:

aqion: input_output_scheme

One Input water – Two Output Solutions

Independent of the chosen path (button Start or Reac) aqion always provides two aqueous solutions:

  •  Output 1 – chemical equilibrium without mineral phases
  •  Output 2 – chemical equilibrium with mineral phases

In contrast, the input water (e.g. water analysis) is neither in a state of equilibrium nor exactly charge-balanced.

According to the above schema, the results of the calculations are presented in tables with three columns: Input, Output 1, and Output 2.

The charge-balanced solution Output 1 (of the left pathway) enters the calculation to examine the carbonate system and the calcium carbonate saturation state.

Two Optional Settings

Two optional settings are available:

  pCO2 to establish equilibrium with atmospheric CO2
  pe value to establish a given redox potential (pe value)

These options simulate a so-called open system where the solution stays in contact with an infinite reservoir of CO2 and/or O2. Thus, in the first option, a definite amount of CO2 is added or removed from the solution in order to establish the given partial pressure of CO2 gas. In the second case, a definite amount of O2 is added or removed from the solution in order to establish the given pe value (redox potential).

[last modified: 2018-04-28]