- chemical equilibria of an ideal gas with pure solids and liquids
T: Units: ,
mass: ,
P: Units:

Mass Species   Mass Species   Mass Species   Mass Species    
 +   +   +   =  ?
Output: Concentration cut-off
Enter up to 4 reactants and 5 elements. Use Compound-Web to list the formula.
Si + 1.5 O2
  - default values
- steam dissociation
H2 + 2 H2S + <1.0e-10> SO2
- note "<>" for exponential quantity
3.5 CaO + 2 Al2O3 + SiO2
- ceramic oxides
CH4 + 0.21 O2 + 0.71 N2
- methane oxidation in air
CH4 + 0.21 O2 + 0.71 N2 + 0.01 H2O
- 4 reactants

Instructions: Specify an equilibrium temperature (within the range 273 to 6000 K), select the units (Kelvin or Celcius; mole or gram; atm or bar), and enter up to 4 reactants containing a total of up to 5 different elements. For aqueous systems, use Aqualib-Web. The default setting is for the reaction between 1 mole of Si and 1.5 mole O2 at 1000 K and 1 atm. The Output options control the type and length of printed output but do not affect the calculated equilibrium; 'Concentration cut-off' drops species below this value from the output; 'Format' displays the results in ChemSage format familiar to ChemSage users, FACT format familiar to F*A*C*T users, or Extended for both; 'Distribution' gives equilibrium distribution of elements in the product phases.

Equilib calculates the most stable products for a given set of reactants. Thermodynamic data are drawn from the pure substances database. Here, in Equilib-Web, you are limited to 4 reactants and 5 elements, and the possible products are an ideal gas phase together with pure solids and liquids at unit pressure and a defined product temperature. Also, non-ideal solutions and charged species (aqueous and gaseous ions) are dropped from the calculation and possible organic species are limited to 4 carbon atoms.

In the complete Equilib module of the package, you may enter up to 48 reactants containing up to 48 elements. Possible products may include non-ideal solutions (real gases, slags, molten salts, mattes, ceramics, alloys, dilute solutions, aqueous, etc.) from the and SGTE solution databases that incorporate various solution models (Margules polynomials, Unified Interaction Parameter Formalism, Quasi-chemical model, Sub-lattice models, Pitzer parameters, etc).

Equilib offers great flexibility in the way the calculation may be performed. For example, a choice of units (wt.%, C, F, psi, CuFt, btu, kwh ...); metastable equilibrium; introduction of activity coefficients; private compound and solution data; aqueous systems (dilute or concentrated); real gases; compressibilities of condensed phases (for the geologists); open or closed system calculations; phase mapping; phase targeting; fixed product activities (Equilib computes the reactant moles); graphical and spreadsheet output for Microsoft Word, Excel, etc.; background (macro-processing) calculations for extremley large systems. You may supply the product temperature, pressure or volume, or you may constrain the approach to equilibrium in a variety of ways such as adiabatic reactions, isentopic, fixed volume change, etc ...

Last updated: March 8 2022 , Christopher W. Bale & Eve Bélisle