TABULATE_REACTION

This command is for the TABULATE_REACTION (TAB) module.

Tabulate thermodynamic property changes for a chemical reaction as a table, or variation of one chosen property can be plotted against temperature as a graph, or saved as an experimental file (with an extension of .EXP). The thermodynamic data are automatically retrieved from the SSUB5 database (by default), or the current database set by the SWITCH_DATABASE command (thus there is no need to use the DATA module before this command). You can select any other database by using SWITCH_DATABASE.

It is important to remember the rules to specify a reaction:

  • The reaction is specified, by giving the reactants and products, such as Ga+S=GaS, 5Al+2Fe=Al5Fe2.
  • Under Linux environments, the notation for a chemical formula treats upper and lower cases as the same (such as ga+s=GaS, 5Al+2Fe=al5fe2); but under Windows, the TAB module only accepts upper cases, e.g. GA+S=GAS, 5AL+2FE=AL5FE2.
  • Elements with a single letter symbol must be followed by a stoichiometry factor, even if it is 1; thus, the symbol CO is taken as cobalt, carbon monoxide must be given as C1O1 (or O1C1).
  • All the reactants and products must be defined as species-stoichiometries in the currently-used database; in other words, the reaction definition only accepts already-defined species-stoichiometries as reactants and products. For example, if a database does not have a species defined with a stoichiometry of Al5Fe2 {e.g. the Al and Fe (but not Al5Fe2) may be defined as species, and the Al5Fe2 phase may be defined as a two-sublattice stoichiometric phase [Al]5[Fe]2, rather than a single sublattice stoichiometric phase [Al5Fe2]}, then the reaction 5Al+2Fe=Al5Fe2 cannot be tabulated.
  • Make sure that the Gibbs free energy expression for a stoichiometric phase is really corresponding to the species-stoichiometry. For example, if a database has a definition of Function GAL5FE2 for 1/7 of the AL5FE2 formula, then the relation G(Al5Fe2)=7*GAL5FE2 must be defined; otherwise, the tabulated thermodynamic properties for the reaction 5Al+2Fe=Al5Fe2 is wrong.

Syntax

tabulate_reaction

Prompts

Same reaction? /Y/:

This prompt displays if there is at least one reaction already defined either with the commands ENTER_REACTION or TABULATE_REACTION. The following prompts only display if N is entered.
 

Reaction: <Chemical reaction equation> & <RA+RB=PC+PD>

A long reaction can be typed over several lines. A reaction should be terminated by a semicolon (;) or an empty line. A list showing the used database, defined elements, getting-data sequence, references, etc.

Pressure /100000/: <pressure of interest, in pa>

Low temperature limit /298.15/: <T-low, in K> Specify the starting temperature K.

High temperature limit /298.15/: <T-high, in K> Specify the ending temperature K. Step in temperature /100/: <T-step> Specify the temperature step for the tabulation.
 

Output file /Screen/: <Return for screen, or type a file name>

If you type Return for screen, a list of thermodynamic property changes for the defined/chosen reaction is shown as a table (which is demonstrated in the example outputs given below), and the command is terminated.

If typing a file name, the table is both displayed on screen and saved as an *.EXP or a *.TAB file, and the program prompts:
 

Graphical output /Y/:

  • For N a table is output to the screen, and the same table is saved as a basic text file with the default extension .TAB under the current working directory. In this case, the graph cannot be plotted.
  • For Y a table is created with all thermodynamic functions as normal (which is displayed on screen) and generates a graph with temperature on the X-axis and a chosen property on a certain column in the table on the Y-axis (which is plotted on screen and saved as an *.EXP file), and it also asks which column is to be plotted on the resulting graph:
 

Plot column? /2/: <1 or 2 or 3 or 4 or 5 or 6>

Specify which property (as column number) to be plotted as the Y-axis (versus temperature as X-axis) as a graph on the screen. Simultaneously, all tabulated properties and the Y-axis setting (i.e. the plotted column) for the graph is written into an *.EXP file using the DATAPLOT format. The default column 2 is heat capacity, 3 enthalpy, 4 entropy and 5 Gibbs energy, and the additional column 6 is a user-entered function. The table displays on the screen. The plot then displays on the screen, followed by a POST: prompt. The POST module automatically opens, and all types of the POST module commands to refine the plotted diagram may be used. Possibilities include scaling the X/Y-axis, changing the X/Y-axis texts, etc. The command BACK or EXIT at the POST: prompt always takes you back to the TAB module.

For the reaction Ga+S=GaS (using the SSUB database), the following table is obtained by typing <Enter> in the prompt Output file /SCREEN/, and the figure by typing 2 in the prompt Plot column /2/:

  O U T P U T  F R O M  T H E R M O - C A L C

   Reaction:  S+GA=GA1S1

stable as S_S

GA stable as GA_S

GA1S1 stable as GA1S1_S

Delta-Cp      Delta-H       Delta-S       Delta-G

(K)    (Joule/K)      (Joule)      (Joule/K)      (Joule)

***************************************************************

298.15  -2.79489E+00  -2.09200E+05  -1.50580E+01  -2.04710E+05

300.00  -2.87516E+00  -2.09205E+05  -1.50755E+01  -2.04683E+05

302.   ---- GA becomes GA_L ,delta-H =   5589.80

367.   ---- S becomes S_S2 ,delta-H =    401.00

389.   ---- S becomes S_L ,delta-H =   1721.00

400.00  -1.22278E+01  -2.17521E+05  -4.07488E+01  -2.01222E+05

500.00  -1.57686E+01  -2.19323E+05  -4.47280E+01  -1.96959E+05

600.00  -1.02518E+01  -2.20583E+05  -4.70410E+01  -1.92359E+05

700.00  -6.58954E+00  -2.21430E+05  -4.83534E+01  -1.87583E+05

800.00  -4.46246E+00  -2.21963E+05  -4.90686E+01  -1.82709E+05

900.00  -2.82671E+00  -2.22328E+05  -4.94995E+01  -1.77778E+05

1000.00  -1.21787E+00  -2.22530E+05  -4.97138E+01  -1.72816E+05

1100.00   3.71702E-01  -2.22572E+05  -4.97552E+01  -1.67841E+05