EQS4WIN runs on Windows 2000,NT,ME,98,95,3.1; it does NOT run well Windows XP. It requires 3M free disk space for all the files. The latest version of EQS4WIN is 2.0.3.

A thermodynamic equilibrium computation is a useful design aid in providing an assessment of the possible behaviors of a complex reacting chemical system. Such a computation is accomplished easily and rapidly using the modern Windows interface and state-of-the-art computational kernel of EQS4WIN. EQS4WIN is ideally suited for both industrial and educational use.

The types of problems which EQS4WIN can treat a broad range of equilibrium problems, as exemplified by the list under the Sample Application Areas topic in the menu at the left. EQS4WIN can also uniquely treat many special problem types, as listed under the Computational Features topic on the menu at the left. These are often very useful in thermodynamic modeling of real systems. These special problem types relate to Reaction Input Data, Stoichiometric Restrictions, and Equilibrium Constraints.

One of the most significant features of EQS4WIN is its ability to solve problems both for which the problem free-energy data is available only as reaction equilibrium constants, as well as those for which individual species data is available (either obtained from its built-in database or supplied by the user). EQS4WIN brings both types of problems under a single theoretical and computational umbrella, making it possible to use a single approach to solve many types of problems. Many of these problems are treated in the literature by special-purpose methods, and the perception exists that they require special-purpose approaches and software. The examples listed under Analytical Chemistry, Aquatic Chemistry, and Biochemistry in the menu at the left illustrate the use of EQS4WIN for such problems.

Other special problem types uniquely treated by EQS4WIN concern the incorporation of Stoichiometric Restrictions (as arising, for example, via kinetic restrictions), and Equilibrium Constraints, by means of which an input feed composition may be determined from a specification of the target equilibrium composition. Treatment of these problem types was pioneered by the research of Prof. W.R. Smith and his colleagues.

The computational kernel which underlies EQS4WIN employs an efficient and robust free-energy minimization method based on more than 30 years of research of Prof. W. R. Smith and his colleagues. Prof. Smith, who acts as a consultant for Mathtrek Systems and supervised the development of EQS4WIN, "wrote the book on this subject". He is the senior author of the text Chemical Reaction Equilibrium Analysis: Theory and Algorithms, W. R. Smith and R. W. Missen, Krieger, Malabar, Fla, 1991; reprint, with corrections, of the same title by Wiley-Interscience, 1982. The state-of-the-art computational kernel of EQS4WIN is not available in any other software package (the book is now out of print, but may be purchased exclusively from this web site; click here.)