WEBCounter by GOWEB


The program calculates and draws thermodynamic equilibrium concentrations of species in complex chemical systems. It handles homogeneous solutions, dissolution, precipitation, titrations with acids, bases, or other components. Adsorption on up to five different particulate surfaces can be modeled with the choice of the Constant Capacitance, Diffuse Layer (Generalized Two Layer), Basic Stern Layer, or Triple Layer model to consider surface charges. Corrections for ionic strength can be made and activities calculated. Kinetic reactions can be simulated with one rate determining process in a system of otherwise fast thermodynamic chemical equilibrium. Two-dimensional logarithmic diagrams, such as pe-pH, or generally pX vs. pY, can be calculated. A drawing option is implemented. A library with over 1750 thermodynamic stability constants allows quick access, comfortable creation of input matrices and hence easy use of the program. A second library contains more than 300 solubility products that can be introduced if solid phases are modeled. Both libraries can be altered and extended with new reactions and stability constants. Output data are formatted for .xls or for import in a graphic program.

ChemEQL is an extended and user-friendly version of the original program MICROQL by John Westall. It runs on MacOSX, Windows, Linux, and Solaris. (For older Mac-operating systems there exists a Pascal-version of ChemEQL V2.0). The program is currently in use in both teaching and research.

A manual guides through the application in a practical way. Many representative examples are included demonstrating typical chemical problems. Download the manual and a folder with example files.

Installation and Start of the Program

ChemEQL 3.1 runs under Java 5 or higher, so all modern operating systems — Mac OS 10.4 or higher, MS Windows (XP, Vista or Windows 7), Linux and Solaris — are supported, namely in their 32-bit- as well as in their 64-bit-versions.

Note that your Web-Browser must have JavaScript enabled to allow for installation and start of the program!

ChemEQL is free for all. However, I ask you to reference this software in case of publication of data calculated with ChemEQL. Please leave me your e-mail and address so I can keep you informed about updates. You may now install and run ChemEQL on your computer by clicking onto the launch button below:

If you do not have an actual Java version installed, this button will lead you to a website from where you can install the latest Java version for your operating system by one click. After this is done, please click the launch button again to start ChemEQL.

For security reasons Java informs you that the identity of the program provider is not certified and that the program will claim access to systems resources (such as printers and the local file system). In order to proceed with the installation, you must accept that.

Finally Java will ask you if it should create a startup icon for ChemEQL on your desktop. It will copy two chemical libraries to your hard disc as well. From then on you may start ChemEQL with the startup icon off-line, i.e. without the need to open a web browser or connect to the internet.


If no orange button is displayed on this page, please make sure that JavaScript is enabled in your browser, f.ex. under MS Explorer 8 you have to find and enable the option "Active Scripting" under Extras → Internet options → Safety → Internet Zone.

In case you encounter problems with the automatic installation of Java, please visit and follow the instructions given there.

©EAWAG, last update 18.11.09, Beat Müller, back to top