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How to use the Ellingham Diagram Web Tool?
There is a three-step procedure to get your Ellingham Diagram using the web tool:
  1. Specify the groups of reactions you interested in
  2. Specify the reactions you interested in
  3. Generate the Ellingham and get the realated calculations
The details of each step are shown below:
Step 1:
In this step, you will be shown a screen as shown in Figure 1. Here you want to select the group of reactions you may interested in generating the Ellingham Diagram. For example: You would like to see the diagram for the following reaction.
4Cu + O2 = 4Cu2O
Then you would check the checkbox by Oxide as shown in Figure 1 and then click on the button says "Go to Step 2".

Figure 1: First Step in using the web tool
Note: You can check multiple groups here if you are interested in multiple reactions which blongs to multiple groups.
Step 2
In this step, you will check the specific chemical reactions you are instersted in. Using the examples shown in Step 1, You will check the checkbox as shown in Figure 2 and then click on the button says "Give me my Ellingham Diagram".

Figure 2: Second Step in using the web tool
Note: You can check multiple reactions here if you are interested in generate Ellingham Diagrams for multiple reactions.
Step 3
As shown on Figure 3, the Ellingham Diagram for the reactions you specified should be shown on the left of the screen. Here, we have used the example in Step 1 for generating the Ellingham Diagram. On the right hand side of the screen, it shows all the related calculation done regarding this reaction.
  • The first bold lines beneath the reactions shows the temperature under which the calculations make sense.
  • The second bold line shows the formula we used to relate free energy to temperature, which is basis of Ellingham diagram and all the related calculations.
  • The Third line is a equation shows how the calculations below are calculated.
  • Then the temperature at which oxide decomposes, as a function of oxygen partial pressure, is calculated. A default value of 1E-15 atm is used here. You can specify the oxygen partial pressure of your interest and then press the "Recalculate Numbers" Button to get your desired condition. If the partial pressure specified will lead to an answer outside the valid temperature range we can calculate using the equation. It will display 'the decomposition temperature is outside the valid temperature range this equation govern'
  • Then Df, Threshold partial pressure for formation, and Equilibrium constant assuming standard reactions will be calculated for a specific temperature, default is 300K. Again, this can be changed by the user and click on "Recalculate Numbers" Button for recalculation.
  • For the oxides system dealing with moisture, PH2/PH2O calculations are provided instead of graphical presentation. To find out PH2/PH2O at a certain temperature. Just input the temperature and click on "Recalculate Numbers"
  • For the oxides system dealing with carbon, PCO/PCO2 calculations are provided instead of graphical presentation. To find out PCO/PCO2 at a certain temperature. Just input the temperature and click on "Recalculate Numbers"
  • To see a trend how Df, Threshold partial pressure for formation, and Equilibrium constant assuming standard reactions change in a temperature range. These values are calculated as well. As showin in Figure 4.
  • Often times, nonstandard reactions are the system that is being examined instead of standard reactions. To gain some info on the non standard reactions, click on DG(T) calculations for non-standard reactions calculation. A new page will open just as shown in Figure 5. After input the different activities for the reaction. Click on "Calculate Now" Button to see the ellingham diagram generated as well as the DG(T) calculations for some temperatures are shown as Figure 6.

Figure 3: Resulting page with Ellingham Diagram and related calculations

Figure 4: Calculations on Equilibrium constant assuming standard reactions within 300k - 2000k for the example reaction.

Figure 5: New window for activity input to calculate DG(T) for non standard reactions

Figure 6: Ellingham diagram and DG(T) for non standard reactions with specified activities.