The method for the determination of the amount of bicarbonates, carbonates and hydrates in water depending on the pH
The author of this article, working in the field of boiler houses, has developed the method for determining the amount of carbon dioxide in steam. The developed method differs from the conventional method. To develop the methodology, it was necessary to understand in what forms carbon dioxide containes in water and how it depends on the pH of water.
This article is devoted to the problem of the research of different forms of carbon dioxide in water. The article deals with the relationship between the three forms of carbon dioxide in water: bound, semi-bound and free in accordance with the theory of buffer solutions. The author also tried to correlate the alkalinity at methylorange and phenolphthalein with pH. Conducting this study, the author received a lot of interesting and useful information about the impact of carbon dioxide on the physical and chemical properties of water.
It is known that carbon dioxide is contained in water in a bound, semi-bound and free form. The bound form includes carbonate ions (CO3), semi – bound bicarbonate ions (HCO3-) and free form carbonic acid (H2CO3).
The total amount of carbon dioxide in water is defined as the sum of all three forms.
СО2 = Н2СО3 + НСО3-+ СО3 (1)
The amount (concentration) of forms of carbon dioxide is measured in mmol/l. These forms of carbon dioxide are in a certain balance. It is commonly said that the percentage ratio of concentrations of different forms of carbon dioxide depends on the pH of the water. Thus, when the water pH is 8.37, there is practically no free form of carbon dioxide in the water and, accordingly, there is only bicarbonate ion and carbonate ion (Fig.1).
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