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Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: AussieKenDoll on April 14, 2019, 11:09:02 AM

Title: How do I read this Fractional composition vs pH graph for EDTA?
Post by: AussieKenDoll on April 14, 2019, 11:09:02 AM

How to get predominant species at a specific pH from the graph?

As an example how do I get the predominant species at pH=10?

My answer is there are few Y4- and more HY3- at pH= 10 and there is no any other forms of EDTA on the solution at PH=10 except Y4- and HY3-. Is this correct?

Title: Re: How do I read this Fractional composition vs pH graph for EDTA?
Post by: AWK on April 14, 2019, 01:16:43 PM

The question requires only one species as an answer. Your answer is a description of the graph fragment, which also correctly indicates the main components for this pH. In every equilibrium all possible species exist; some, of course, in negligible quantities.
Only at pH=pK_x answer should contain two species.