Calculate pH of seawater
토픽 개요
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In the previous problem, we derived an equation for the percentage of each carbonic acid component to [DIC] at a given pH. Please prepare paper and pencil and calculate the following equation to state. [HCO3-] = (function of [DIC] and [H+])
Formula (1) [DIC] = [HCO3-] + [CO32-] + [H2CO3]
Formula (3) K1 = [HCO3-]・[H+]／[H2CO3]
Formula (4) K2 = [CO32-]・[H+]／[HCO3-]
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Finally, we come to the main issue.
Did you know that the pH of seawater is 8? Find the pH of seawater by giving the partial pressure of carbon dioxide in the atmosphere (pCO2) and the concentration of total carbonic acid (DIC).
(Notice) In this problem, I gave the DIC concentration when determining the pH of the seawater. So how is the DIC of seawater determined? Once two of the four parameters, DIC, pH, pCO2, and alkalinity, are determined, the others can be determined. pCO2 is dominated by the atmospheric side. Alkalinity is dominated by the weathering of the rocks on land. Please wait for a while.
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I assume that you all used paper and pencil to write the equation in the middle of the above problem to derive the formula for pH. I asked you to use Excel to calculate [H+] and pH. If the final results are different or you are not confident about the middle formula, please check this page.
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