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Unformatted text preview: Sketch the fractional composition versus pH curves arising from the relevant to the
triprotic acid H3A(aq). Clearly label your plot and mark the special points. Show the derivation or proof of
two special points that involve a fundamental physicochemical property of the fully protonated acid.
If you have no idea, you can get up to 60% credit by correctly answering this question for the diprotic
system, H2A(aq), instead. You should know that there are going to be 4 principal species and two of these species are amphiprotic
giving rise to an “intermediate” form. The intersection points (the special points) are all labeled.
Derivation of special point 1 involving : when , and , common denominator determined by the mass balance,
.
Derivation of special point 2 involving (D is a
) so that : . When
procedure as above) and so the two curves must intersect. , (shown by the same 6. [40 marks] Which two of the following compounds (all derived from the triprotic acid) would you mix
to make a good buffer at pH 7.45, and why would you choose t...
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This document was uploaded on 03/12/2014 for the course CHM 212 at Rhode Island.
 Fall '11
 N/A

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