[OLD] Act2 axes variables

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From: William F. McKenzie

Subject: Act2 Axes Variables

I would like to make an activity diagram for the K2O-Al2O3-SiO2-H2SO4 system; e.g., considering the phases K-feldspar, Pyrophyllite and Alunite; balancing on Al+++; fixing a[siO2(aq)] with Amorphous Silica solubility; and plotting log a(K+)/a(H+) vs log [a(SO4--)][a(H+^2)]. However, I am unable to swap SO4--*H+^2 for SO4--, trying the following:

Act2> swap SO4--*H+^2 for SO4--

-- Species H+^2 is not a known basis species

Act2> swap SO4--*H+*H+ for SO4--

-- Species SO4-- can only be swapped in for:

SO4--

Act2> swap H+^2*SO4-- for SO4--

-- Don't know species H+^2

Act2> swap H+*H+*SO4-- for SO4--

-- Swap species H+ is already in the basis

 

Is there a trick that I have overlooked?

 

From: Craig Bethke

Subject: Re: Act2 Axes Variables

The GWB doesn't recognize the “*� syntax for an activity product. Instead, you use the “/� syntax for an activity ratio, using a negative exponent: swap SO4--/H+^-2 for SO4--