Basic command TOT

[Zhaoyang]

Hi, all,

I want to obtain the total molality of an element, but I get different results from TOT("K"), TOT("K+") and TOT("K(1)"). Does anyone know the reason? Any help will be appreciated.

Best regards,
Zhaoyang

[dlparkhurst]

The argument of TOT is either an element or an element redox state. For potassium, only TOT("K") is defined. For PHREEQC, elements are named with capital letter followed by zero or more lower case letters, so K+ is not an element name. No redox state K(1) is defined in any database that I know of.

For example, K, C, C(-4), C(4), S, and S(6) would be legitimate arguments for TOT.

[Pak]

I have a small question probably dumb and maybe even explained somewhere related to the TOT() function and valance species.

Imaging in my database I have the following elements and an element redox state defined:

Se            SeO4-2         0            Se            78.96
Se(+4)        SeO3-2         0            Se            78.96
Se(+6)        SeO4-2         0            Se            78.96
Se(-2)        HSe-           0            Se            78.96

can I assume that TOT("Se") = TOT("Se(+4)")+TOT("Se(+6)")+TOT("Se(-2)")?

[dlparkhurst]

Yes.

There is a subtle database rule that only "secondary master species" are defined with e-, O2, or H2 in their reactions in SOLUTION_SPECIES. In your case, the only selenium reactions containing e-, O2, or H2 would be  SeO3-2 and HSe-. This rule is necessary to ensure that the TOT method gets the correct total for each redox state.

[Pak]

cool, thanks.