Chemistry files

A “chemistry file” defines a chemical equilibrium system in terms of:

  • phases
  • primary entities
  • entities
  • reactions


A phase is a part of the chemical system with an individual mass balance for entities.

Examples phases are:

  • “diss”  (dissolved),
  • “ads” (adsorbed),
  • “min” (mineral),
  • “tot” (total),
  • “gas” (gaseous)

Phases can be defined in an hierarchical way to link their mass balances. The tot phase can for example be composed of a solution, a gas and a solid phase:


@phases(liter, tot, watervolume)

@phase(gas, tot, gasvolume)

@phase(min, tot, 1)


An entity is a kind of abstract species that can be used in formation reactions.

An entity has a log activity (<name>.logact)  and a concentration (<name>.con) and is defined in one of the system phases.


@entity(e-, diss)

Derived forms of entities are: species, gases, minerals, sites, solid solutions, electrostatic planes etc.

Primary entities are the equivalents of “master species” or “components” in other programs. Primary entitities are the independent base entities from which all other entities can be formed via formation reactions.