CO2 gas was passed for long hours to know whether Na2CO3 forms in the starting for a short period of time or it does not form at all, NaHCO3 forms and I guess is the final product of the process, after long hours.
Thanx daniel for the info..
I am interested in the said transformation of NaOH - Na2CO3 - NaHCO3 according to time, CO2 amount passed, etc. parameters as I am not able to realize the formation of Na2CO3 indeed directly NaHCO3.
For details read my articles and literature in:
Glade, H.; Al-Rawajfeh, A. E.; Modelling of CO2 Release and the Carbonate System in Multiple-Effect Distillers. Desalination, 222 (2008), 616-636
and
Al-Rawajfeh, A.E.; Modelling of Alkaline Scale Formation in Falling-Film Horizontal-Tube Multiple-Effect Distillers. Desalination, 205 (2007) 124-139
When a certain total carbon dioxide content (TC) is dissolved in seawater, it is important to know which fraction thereof is present as CO2, which as HCO3– ions and which as CO32– ions. The distribution of the species depends on the pH
value, the temperature and the ionic strength. See Fig. 3 in the 1st article and Fig. 2 in the 2nd one.
Directly will not be formed NaHCO3 if NaOH is in excess, and in the solution there is no Na2CO3 or NaHCO3, only ions, namely Na+, OH-, or depending on the pH CO32- or HCO3-. So, the ratio of NaOH/CO2, and the concnetrations, pH are the main factors, what will be cyrstallized out (Na2CO3, some of its hydrate, or NaHCO3), but in the solution, depending on the pH and NaOH concn., always an equilibirum mixture will be present.
thanks laszlo, pesence of the equillibrium could never be denied but i am going for the majority or let say extremely feeble presence of other constituents, which i hope should be NaOH in the beginning, that goes to Na2CO3 just after starting purging of CO2 and eventually goes to NaHCO3.
I am still searching for more detailed explaination and mechanism.
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