3. Reaction

Content
3.1. General
3.2. Important Menu Functions
3.3. Possible Errors

3.1. General

The application shows the changes of thermodynamic state function in dependence of temperature and pressure by a reaction in tables and graphics

Enter a reaction equation in the table window and press the button update.
Reactants can be written with or without phase description, e.g.:
H2(g)+1/2O2=H2O(g)
Cd(OH)2 = CdO + H2O

When no any phase description is given, the application regards the state, which has minimum free energy at given Temperature and pressure.
Possible changes are written in the table.
The equation for the initial reaction including the aggregate states is given in the status line (bottom) of the table.
For the reaction H2+1/2O2=H2O
In the initial reaction, H2O is H2O (l) if the first line of the table shows 50 °C and 1 bar.
In the initial reaction, H2O is H2O (g) if the first line of the table shows 300 °C and 1 bar.

The state functions can also be extrapolated if those data are not available and extrapolation is admitted

Examples:
Fe2O3 = 2FeO+ 0.5 O2
Fe2O3=2FeO+ 1/2O2
Fe2O3=2Fe+3/2O2
Fe2O3=2Fe+1.5O2

3.2. Important Menu Functions
System -> behaviour: You can determine, according to which behaviour the state functions of the gases are to calculate. The state functions can be calculated according to the real gases laws, when the critical data (Tc, Pc) of the gases are known in the database.

System -> Select from Database:
The menu shows a window, in which substance of equation can be selected.
The elements can be specified by Button Elements, which the substances should contain.
When the buttons for the elements are pressed in the Elements window, the colours will be changed to red or blue. The selected elements are shown in red. When Button Accept is pressed, the substances are shown in Substance Window.
Mouse left double click on the Substance Window adds the selected substance in the equation oft the the table window, or Button Accept can be used.

System ->Graphic: Graphic Window usually shows the change of the state functions in depend of the temperature or pressure.

An other graphic variable can be defined by menu in Graphic Window Graphic->User Defined

When Graphic->User Defined is selected, the menu Graphic -> Variable definitions shows the following dialog box, in which the graphic parameters can be selected individually.

More details are explained in 7.Graphic.

Dimension mass can be select, when a equation already calculated.
After the first calculation, the reactant can be specify by drag down box (combo box) for reaction equation.
When you select a reactant or product of the reaction, the menus [g] and [kg] can be enabled to select.

Information:
Information -> help: displays this text.
Information -> messages: recent error messages are listed in a separate window.
Information -> About Reaction: information on software, version is displayed
3.2. Possible Errors
If the datasets of a substance contain gaps, then calculations of the applications Pure Substance and Reaction can be erroneous.
Therefore, datasets of a substances should not contain any gaps.
For example: when two datasets exist for a substance in the database
first from 300-500 K and
second from 600-1000 K.
A calculation between 400 K and 700 K will not consider the second dataset from 600-1000 K.