Reaction stoichiometry for oxidation of Nta (Example 15)

[MichaelZ20]

Hello!
I have a question about example 15 in the PHREEQC manual. I don't understand why consumption of elements by "chemically inert" C5H7O2N in reaction of HNta2- oxidation is not included in the reaction stoichiometry for -formula in KINETICS block. The reaction is:
HNta-2 + 1.62O2 + 1.272H2O + 2.424H+ = 0.576C5H7O2N + 3.12H2CO3 + 0.424NH4+.
Following the Monod rate expression, C5H7O2N indeed does not influence the rate, but the same role play also H2O, H+, H2CO3 and NH4+ that are considered.
Thank you in advance for the explanation!
Sincerely,
Michael

[dlparkhurst]

The Nta example was designed to compare codes, so the reactions were defined by the people that made up the example.

You certainly can remove H3Nta and add N(CH2CO2H)3 for the -formula to account for the oxidation reactions.

[MichaelZ20]

David, thank you for your reply!