yzdm
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Posts posted by yzdm
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5 hours ago, Brian Farrell said:
Hi,
You can set most basis entries as bulk or free constraints. For a bulk constraint, the value you set refers to the entire thermodynamic component, whereas for a free constraint, it refers to the particular species only. The HCO3- component, for example, might include the HCO3- species, as well as CO2(aq), CO3--, NaHCO3, etc. If you set 10 “mg/kg” HCO3-, the concentration is for the sum of those species. If you set 10 “free mg/kg” HCO3-, though, the concentration refers only to the individual HCO3- species. An additional amount of carbon exists as the other species.
Likewise, for H2O, “free kg” refers to solvent H2O only. If you change the setting to simply “kg”, the mass you specify refers to the sum of solvent H2O plus species composed of water (e.g., Al(OH)4- + 4 H+ = Al+++ + 4 H2O). For more information, please see 7.1 Example Calculation in the GWB Essentials Guide.
Log refers to the base 10 log of a number (e.g., 1 free kg H2O = 0 free log kg H2O). A more common use is for setting the CO2 fugacity or partial pressure using logs (e.g. log f CO2(g) = -3.5).
In the future, please don’t post topics multiple times.
Regards,
Brian Farrell
Aqueous Solutions
Thanks for your reply. There is something wrong with the internet connection yesterday. The webpage displayed submission failed. I will pay attention not to submit multiple times.
Anyway, thanks.
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Hi there, here is a question.
What is the difference between the units: kg/free kg/log kg/ log free kg?
Any special meaning?
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Here is a detialed description.
I ran a reaction under temperatures from 350 to 200 and at the temperature of 300, 250, 200, respectively.
For example, i compared the amount of products at 300 (the reaction conducted from 350-200), however, these amounts are different from the value when i ran the same reaction at the temperature at 300.
Why does this happen?
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Hi everyone, i made a comparison between the databases from GWB and EQ3/6. There are content differences between these two databases.
The database content of EQ3/6 is similar to that of GWB, and the titles in the same line of the table below have similar content from No. 1 to No. 8. And No. 10&11 of EQ3/6 are break up and filled into other contents in GWB. However, the content of 'Solid solutions' in EQ3/6 and 'Oxide' in GWB seem to be the distinctive content in each database.
I want to ask whether the database of GWB contains 'solid solution', if not, what effect will have on the simulation result?
No. EQ3/6
GWB
1 Title including Options
Header (References)
2 Miscellaneous parameters
Tables
3 Elements
Elements
4 Basis species
Basis species (B-dot parameters)
5 Auxiliary basis species
Redox couples (B-dot parameters)
6 Aqueous species
Aqueous species (B-dot parameters)
7 Solids
Minerals
8 Gases
Gases
9 Solid solutions
Oxides
10 B-dot parameters
11 References
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Hi Brian Farrell,
Many thanks, everything goes well now!
10 hours ago, Brian Farrell said:Hi,
You can't add a reactant to a system unless that system already includes the components that make up the reactant. The components need to exist in the initial definition of the thermodynamic model, even if in a negligibly small concentration. All you have to do is set very small amounts of B(OH)3(aq), Li+, Mg++, etc. in the Basis.
Hope this helps,
Brian Farrell
Aqueous Solutions LLC -
Hi, recently, i would like to run a model of reactions between glass and water. Oxides are used as the reactants on behalf of glass. However, errors occurred when i ran the react like below:
-- Error: Can't react B2O3(ox) because the system doesn't include B(OH)3(aq)
-- Error: Can't react Li2O because the system doesn't include Li+
-- Error: Can't react MgO because the system doesn't include Mg++
-- Error: Can't react TiO2 because the system doesn't include Ti(OH)4(aq)
-- Error: Can't react Cr2O3 because the system doesn't include CrO4--
-- Error: Can't react Cs2O because the system doesn't include Cs+
-- Error: Can't react F2(g) because the system doesn't include F-The react file and database are attached below. Species mentioned above "B(OH)3(aq), Li+, Mg++, Ti(OH)4(aq), CrO4--, Cs+, F-" are all under the 'Basis species' but none under the 'Aqueous species'. I suppose this may be the reason for errors. However, how can i solve this problem?
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I have found the answer now. There is no need to reply, cheers!
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Hi guys, i want to make a comparison between EQ3/6 and GWB about a simple water-rock reaction on the base of the same thermodynamic database. The final results seem to be alike, but the processes of the reaction have much difference. I guess the algorithms used by these two software cause the situation. A hybrid Newton-Raphson algorithm is employed in EQ3/6 during the reaction. However, i don't find the algorithm that GWB used during reaction. So i am here asking for help. ONE MORE, why can i only start a topic on the student forum?
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Recently, i want to run two reactions, the second one is on the basis of the first one. After running the first reaction, i use run-pick up-system-entire, but an error occurs.
However, this situation doesn't occur all the time, just in a small range of amount of reactant. The reaction files and database are attached below.
I don't know what's wrong, so i am here asking for help.
!What's more, aftering reading the content about redox pivot, i decoupled "HS-/SO4--" and solved this problem. But the sulfide won't form in the reaction. I am not sure what happened inside.
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On 2017/11/25 at 5:22 AM, Brian Farrell said:
Hello,
As I recall, you have a licensed version of GWB Standard, which includes the React app. This allows you to perform many calculations and analyses not possible with the free Student Edition software.
First of all, are you calculating reaction path simulations or are you interested only in equilibrium state. If you're only interested in equilibrium state (what you can calculate with SpecE8), then instead of running a series of discrete simulations at different temperatures, you can set up a simple polythermal path ("sliding temperature") to scan over a range of temperatures. As for water/rock ratio, the best strategy depends on how exactly you define the ratio, but one simple idea is to add your mineral(s) as simple reactants (a "titration path"). As the reaction path proceeds, you react more and more mineral mass into a body of water, thus considering a range of water/rock ratios. Again, whether or not this is appropriate depends on how you exactly you define water/rock ratio.
Second, are you aware of React's pickup feature? With the pickup feature, you use the results of one calculation as the starting point for another. For more information, please see 3.9, Picking up the results of a run, in the GWB Reaction Modeling Guide.
Finally, if you're already setting up a multitude of reaction path calculations, you might wish to programmatically run and retrieve results from GWB calculations. There are a few ways to do this in the GWB. They're described in the GWB Reference Manual in chapters entitled Report Command, Control Scripts, and the Plug-In Feature.
Hope this helps,
Brian Farrell
Aqueous Solutions LLC
Hi Brian Farrell,
Thank you for your reply. It maybe work, however, i need time to learn the methods. And i will ask for your help, if more questions occur to me.
Best
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Hi, everyone,
I need to run a series reaction files under diffrent w/r ratios and temperatures, which is about 126 reacions in total. This is only the first step.Moreover, i also need to run new reactions on the basis of the results of the first step.
As we can see, i may collect the concentrations or values of the products, the pH, the logfO2 and some elements in the fluid about the 252 reactions. I did it once, which took me about four days. It is too time consuming, so i want to ask for help!
Is there any convenient way for users like me to get what i want.
Thank you guys.
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Hi,
You can go to the Config -> Output dialog and adjust the three-way checkboxes in the "include" section under "print dataset". Looking at mineral saturation, for example, an unfilled box will cause no saturation indices to be written to the print dataset, a checked box will cause saturation indices above -3 to be written out, and the completely filled box will cause all saturation indices to be written. For more information, please see 2.8, Controlling the printout, in the GWB Reaction Modeling Guide.
Gtplot can draw a wide variety of plot types from React output. Even if it doesn't have the special charts that you're interested in, Gtplot provdes a very handy method to export numerical values in a format that you can paste directly into a spreadsheet like Excel. This is almost always easier than copying values from the text output file. For example, make an XY plot with mineral saturation on the Y axis, select all the minerals, then go to Edit -> Copy in Gtplot. When you paste into Excel, you'll have a nice table of all your mineral saturation indices. For more information, please see 6.7, Exporting the plot, in the GWB Reaction Modeling Guide. To see a slideshow of how this works, please go to https://www.gwb.com/tutorials.php#USING_GWB and click on the "How do I retrieve numerical data from my plots?" tutorial.
Finally, I noticed a pair of warning messages at the bottom of the Results pane. I'd be happy to take a look at them if you attach your script.
Regards,
Brian Farrell
Aqueous Solutions LLC
Hi, Brian Farrell,
Thank you every much for you kindness help. It works well now. The warning messages only occur under temperatures below about 140℃ due to the mass imbalance of -e. The database file was too large to upload, so i just uploaded the rea file.
Regards,
Chen
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Hi, there,
I was runing a series of reaction files and i need pick up the results and draw some special charts.
However, when i click the 'view results' button, the results are incomplete like below.
So, anyone can tell me where to change the setting in order to show the full results, please?
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Hi Melika Sharifi,
We can get log(SO4--/H2S) = logK + 2logO2,aq, according to H2S + 2 O2 - = SO42- + 2 H+.
I suppose ' O2 - ' in the reaction means 'O2,aq' actually?
Bests,
ChenYang
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Hi there,
I have a question when i read a pic like this:
What is that mean by saying:"O2 activity is expressed as SO42-/H2S". Any more information can be delivered?
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Got it, thank you for you advices
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Ok, many thanks
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Hi everyone,
After learning the tutorial about “Editing thermo”, i noticed that the range of temperature and pressure are limited. I do know how to modify the logK vaules using SUPCRT92, but i am not sure how to change the parameters of Deby-Huckel parameters/CO2activity coefficient terms and water activity coefficient terms, especially the CO2 1,2,3,4s and H2O 1,2,3,4s.
Where can i find those parameters or is there a software can generate them?
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Here is my problem:
I met a problem when i try to rebuild the figure below, which is under the T 215℃ and P 250bars:
And my dashboard is like this:
When i want to run it, a window come:
So i can't go on to test the first figure.
Can anyone tell me what's wrong, please?
And How can we put two temperatures:215 and 90℃ into one figure?
Thanks a lot!
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Hello,SUPCRT92 is a program used to calculate thermodynamic properties (log Ks, equilibrium reactions, etc.) at almost any temperature or pressure. Most GWB users are able to utilize the thermodynamic datasets distributed with the software. However, a user may want to account in their calculations for species or minerals not included in the GWB datasets, or to use data derived from more recent and higher quality experiments, or a user might want to run calculations at P-T conditions that are different from those set in the GWB’s defaults datasets. In these cases, a user might search for log K values in a different dataset or in the literature or use a program like SUPCRT92 to calculate the log Ks from other types of thermodynamic data.Hope this helps,KatelynAqueous Solutions LLC
Hi Katezat
Thank you very much. It is very useful for me to learn this.I have a clear understanding now.
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I am trying to generate activity-activity plots for the following reaction:
Andalusite+Celadonite = Margarite + Muscovite
I have calculated Thermodynamic data which includes the Log K for this reaction using SUPCRT92 (Johnson et al 1992). How do I incorporate this data within Act2 to generate a stability diagram that represents the activity of my reaction?? I have attached a sample of the type of diagram I need to plot.
Please Help!!
Hi Tanzil Deshmukh,
I noticed that you use the SUPCRT92 to generate a thermodynic dataset. I don't know how to use this software to generate a dataset, so do you have any tutorials to show the process.
Best Regards.
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Hi
I am new in learning GWB to model some process in geochemistry. Before GWB, i was trying to learn how to use EQ3/6, which is not very friendly to new learner. And i was confused by the function of SUPCRT92, it seems that we have to use it to generate new therodymatic datasets for GWB/ EQ3/6.
However, GWB has its own datasets, why do we still need SUPCRT92?
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Hello Tanzil,
You can easily modify thermodynamic datasets in the GWB using TEdit (under the support tab on the GWB dashboard). It's always a good idea to start by opening an existing dataset and saving it to a different name before modifying it. For more information, see the TEdit section in the GWB Essentials Guide (you can access PDFs of the user's guides from the Help menu of any GWB program, or from the Docs pane of the GWB dashboard). You can also view tutorials on how to edit thermo datasets here. Once you have completed your thermo dataset you can load it into Act2, go to File ->Open->Thermo Data... (or Ctl+T) to select the thermo dataset you would like the program to reference.
Kind regards,
Katelyn
Aqueous Solutions LLC
Hi Katezat,
I am very glad to read your answer. I am learing GWB for the modeling need in geology. I was still confused by the function of SUPCRT92, GWB has its own thermodynamic datasets, why we still need supcrt92 to generate the new dataset, and do you know any tutorial about how to use SUPCRT92.
Thank you very much!
Best Regards
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Hi Eric,
I've made one that may be meet your request since i don't know your exact parameters so i set some myself.
However, i don't know how to upload the picture, so if you still need it, send me a emial.
Difference between an open and closed system?
in The Geochemist's Workbench
Posted
I do not quite understand the differences between an open and closed system.
In my view for a closed system, the amounts of reactants and fluids are given at first, then the reaction goes ahead, resulting in the decomposition of reactants and the formation of products. None of the reactants and fluids is fixed.
As a contrast, one or some components of the reactants and fluids is fixed during the reaction.
I am not sure whether my understanding is correct or not, so any suggestions are welcomed.