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# can't retrieve H+ molal in python script

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Hello everybody,

I can't retrieve the molal H+ concentration. With

#######

species = myGWB.results("species")
conc = myGWB.results("concentration aqueous", "molal")
print "\nThere are" , len(species) , "aqueous species.\n"
for i in range(len(species)):
print "%-4s = %10.4g mol/kg" % (species, conc)
print "concentration H+ = ", myGWB.results('concentration H+', 'molal')[0]

#######

I get

Y:\Rechnungen\gwb>0001_test.py

There are 9 aqueous species.

H+   =  3.027e-07 mol/kg
HSO4- =  3.231e-06 mol/kg
K+   =     0.7233 mol/kg
KMg(SO4)+ =  6.463e-05 mol/kg
Mg(OH)+ =  3.447e-06 mol/kg
Mg++ =      3.114 mol/kg
Mg3(OH)4++ =  8.826e-15 mol/kg
OH-  =  8.746e-08 mol/kg
SO4-- =      3.475 mol/kg
concentration H+ =  -3.47366172108e-10

It seems that with myGWB.results('concentration H+', 'molal')[0] I retrieve something else (charge balance?) but not the H+ molality. Of course I could work around the problem and get the H+ molality from the aqueous species list,  but this wouldn't be elegant.

Helge

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Hi Helge,

Concentration H+, molal will give you the concentration of component H+ which refers to the sum of all species with H+, such as HSO4-, OH-, Mg(OH)3, etc. If you want to get the concentration of a particular species, such as H+ which is called free H+, you will need to add "aqueous" to your command (i.e. ('concentration aqueous H+', 'molal﻿').

Hope this helps.

Bests,

Melika Sharifi

Aqueous Solutions LLC

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Means: if I want to retrieve the total molality of Tc(+IV) in solution, and TcO(OH)2 is the secondary master for the formation of all Tc(+IV)-species, I use

myGWB.results('concentration TcO(OH)2', 'molal')[0]

?

Helge

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Hi Helge,

It will give you the total concentration of Tc in your system (all oxidation states), unless you have decoupled Tc(IV) from other states.

Bests,

Melika

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Taken the case I look at the transition of Tc(+VII) to Tc(+IV) by inreasing pH: is there any means to retrieve the proportion of the two different oxidation states of Tc in solution?

Helge

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Hi Helge,

I'm not sure which dataset you are using, so I am not able to give you an exact response. It looks like in your script, you have not decoupled Tc(VII) from Tc(IV). If you use "aqueous" in your command, it will give you the free concentration of that specific species in solution. Consider thermo.tdat dataset when Fe(II) is not decoupled from Fe(III),  myGWB.results('concentration aqueous Fe++', 'molal')[0]﻿﻿, will give you the concentration of Fe++ aqueous species, and myGWB.results('concentration aqueous Fe+++', 'molal')[0]﻿ will give you the concentration of Fe+++ aqueous species. While myGWB.results('concentration Fe++', 'molal')[0]﻿﻿, will give you the total concentration of component Fe(II), and myGWB.results('concentration Fe+++', 'molal')[0]﻿ will give you the total concentration of component Fe(III) (i.e. all species with Fe(III) such as Fe(OH)3, Fe+++, Fe2O3, etc).

Hope this helps.

Bests,

Melika Sharifi

Aqueous Solutions LLC

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