Mr. Parkhurst: Hi, how are you ! I am very appreciated of your help on my question last time . I don't know if you had time to think over the question on caron dioxide. I remembered that you said you were out of town for two weeks. I sent a email to you then and i am not sure if you got it. So I here sum it up in this way: I am trying to simulate the disolution of the gas composition of air in solution which is bubbled with a humidified air in lab experimental condition. The concentration of carbonate is unknown. I tried to set the initial data in GAS_PHASE 1 Air -fixed_pressure -pressure 1.0 -temperature 25.0 CO2(g) 0.000316 O2(g) 0.2 N2(g) 0.78 as well as EQUILIBRIUM_PHASES 1 Fix_H+ -8.0 NaOH 10.0 CO2(g) -3.5 O2(g) -0.69897 N2(g) -0.1079 The pH are set as fixed from 2-10. There are 1 mg/l U in the soultion and adsortion by iron oxide are allowed too. The first one comes out with the carbonate distribution as shown in attached file while the second one doesn't converge. I tried the KNOBS data but didn't work. Butwhen I took away the O2(g) and N2(g) from the data set, it gave a fairly good result. Here is my questions: 1. which one data set should i use to represent the experimental condition ? 2. I used the Fixed_H+ for constant pH. In order to keep the acid-base and calculation balance, I need to assumed some acid or base present as Manual recommended. Don't they influence the chemical reaction, such as to increase or decrease the dissolution of CO2 ? how to avoid using the assumed acid or base ? Any advices if necessary? Thanks a lot for your precious time and help. Yours sincerely, Young Wang Department of Geology SUNY-Binghamton
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