ChemReaX is a web app for modeling and simulating basic chemical reactions. The
software is intended for chemistry students and their teachers at the
undergraduate and high school (AP) levels. It supplements classroom learning,
laboratory experiments and textbooks. It utilizes sophisticated simulation
techniques under the hood to open up an exciting new dimension in the learning
and teaching of science. ChemReaX can be used to explore a nearly unlimited
variety of chemical reactions and perform what-if experiments with reactions.
The focus of the current version of the software is chemical thermodynamics,
chemical equilibrium and reaction kinetics. Thermodynamic properties for over
1200 chemical species are included, allowing students and teachers to model and
study a large range of chemical reactions.
Reaction variables include: choice of reactants and products, initial
concentrations, temperature, and a pressure factor.
Questions that can be answered include: Is it possible for a reaction to occur?
In which direction will the reaction proceed given an initial state? Is the
reaction spontaneous? What is the final equilibrium state? What if there is a
limiting reactant? How does the reaction respond to changes in temperature and
initial concentrations of reactants/products? How fast does a reaction proceed
and how do the reactant/product concentrations change over time?
ChemReaX typically used?
ChemReaX can be used as a virtual lab or testbench to model and simulate a
nearly unlimited variety of chemical reactions. The 1200+ chemical species in
the ChemReaX database can be combined together as reactants or products in a
chemical reaction, covering most reactions of interest to chemistry students and
teachers. Reactants and products are selected using the drop-down lists. The
user is expected to balance the chemical reaction by entering the correct
balancing coefficients (we will soon add a feature to check for errors in
balancing). The user then enters the initial concentrations of the reactants and
products. Temperature, pressure factor and reaction rate parameters are
additional variables that can be set by the user. When the "Run the Reaction"
button is pressed, ChemReaX performs equilibrium calculations and then simulates
the reaction until a final steady state is reached. Results are provided in
tabular and graphical forms.
Some typical applications:
- Run virtual
"experiments" and collect data for lab exercises on any number of chemical
Put together any reaction of interest using the
1200+ chemical species in the database. Currently up to to three reactants and
three products can be chosen. This allows for a nearly unlimited number of
reactions to be studied.
Vary initial concentrations of all
reactants/products, as well as temperature, and “run” each reaction under
Data collected from the virtual experiments may
include final concentrations of all substances, overall free energy change,
overall standard enthalpy/entropy changes, and other details.Model the reaction
rate as an additional option to study reaction kinetics and thermodynamics in a
New: Vary the pressure factor relative to
a baseline to see the effect of pressure changes when a reaction is at
New: Run simulated titrations to study
acid-base interactions. Choose from a large selection of strong/weak acids and
bases as titrands, and vary the titrand and titrant volumes and concentrations.
Predict the outcomes of any reaction and compare with ChemReaX results:
Predict the direction of the reaction from a given
initial state at a given temperature -- and then compare with simulation results
Hand-calculate the equilibrium state and final
concentrations (including the effect of any limiting reactants) -- and then
compare with simulation results from ChemReaX.
Predict the effect of effect of variations in
temperature, pressure and initial concentrations on the final equilibrium state
per Le Chatelier's principle -- and then compare with simulation results from
Predict the result of an acid-base titration --
and then compare with simulation results from ChemReaX.
Apply Hess's law to break up a complex equation
into a set of simpler additive equations for thermodynamic calculations. Get the
free energy change (∆G) for each simpler equation from ChemReaX and
compute the overall free energy change, and then compare with ChemReaX results
for the single complex equation.
thermodynamic properties (standard molar enthalpy of formation and entropy at a
specified temperature) for any of the 1200+ species in the database for use
outside of ChemReaX. This is the largest free online database of chemical
thermodynamic properties as a function of temperature.
validity of a chemical equation by verifying that mass and charge are conserved.
unique about ChemReaX?
ChemReaX allows users to construct a virtually
unlimited variety of chemical reactions using the 1200+ species in the internal
database, and automatically verifies the validity of the equations. It also
comes with over 80 pre-defined reactions that can be quickly selected under 10
ChemReaX actually simulates a given reaction from
the initial conditions until it reaches a final equilibrium state (using an event-driven simulation algorithm),
and accurately generates the final concentrations of all reaction components.
ChemReaX can run
the simulation utilizing a user-provided reaction-rate model (using a time-driven simulation algorithm),
and display the reactant/product compositions graphically as a function of time.
ChemReaX can evaluate the effects of pressure
changes at equilibrium and produce the pressure-adjusted final compositions of
products and reactants.
Additionally, ChemReaX can simulate acid-base
titrations based on simulations of incremental titrant volumes, utilizing the
same underlying simulation technology used for general reactions.
ChemReaX puts a powerful modeling and simulation
capability in the hands of chemistry students and teachers. It is not an
animation tool, but a real simulation tool -- similar to tools used in industry
-- that can help with serious scientific study and inquiry.
the largest free online database of chemical thermodynamic properties as a
function of temperature.
ChemReaX is web-based and hosted on the cloud.
There is nothing to install on the user's computer and any web browser will do
for accessing the tool.
free to use?
Yes, ChemReaX is absolutely free at present. A basic set of functions and
capabilities will always remain free for all students and teachers to access
from anywhere in the world.
How can users
participate in the further development and evolution of ChemReaX?
As you use this software tool, please let us know what you like, what you don't
like, and what features should be added or improved for a better learning
experience. We absolutely need your input and help to make the idea of
teaching/learning science by simulation a reality. We especially want
to hear from you if you are a teacher/professor and are interested in
incorporating this technology into a chemistry course that you are teaching. The
technology is here, let us work together to perfect it. Please contact us at
What are the sources of the theory and data used in
Pauling, L. 1988. General Chemistry. New York: Dover Publications.
Atkins, P. and De Paula, J. 2014. Physical Chemistry: Thermodynamics,
Structure, and Change. New York: W.H. Freeman & Co.
DeVoe, H. 2014. Thermodynamics and Chemistry.
Rosenberg, J.L., Epstein, L.M., and Krieger, P.J. 2013. College Chemistry.
Schaum's Outline Series. New York: McGraw Hill Education.
Cox, J. D., Wagman, D. D., and Medvedev, V. A. 1989. CODATA Key Values for
Thermodynamics. New York: Hemisphere Publishing Corp.
McBride, B.J., Gordon, S., and Reno, M.A. 1993. Coefficients for Calculating
Thermodynamic and Transport Properties of Individual Species. NASA
Technical Memorandum 4513.
Goldberg, R.N., Kishore, N., and Lennen, R.M. 2002. Thermodynamic Quantities
for the Ionization Reactions of Buffers. J. Phys. Chem. Ref. Data, Vol. 31,
Dill, D. 2008.
Notes on General Chemistry. Department of
Chemistry, Boston University.
CRC Handbook of Chemistry and Physics, 84th Edition.