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Monoprotic Titration Curve

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A model of the titration curve of a weak monoprotic acid titrated by a strong base. You can change the titrant concentration and the pK, volume, and concentration of the acid by typing in their values at the top left of the screen or by using the sliders. (I find the sliders easier to use in a darkened lecture hall where I can't see the keyboard easily).

A dynamic model like this allows interactive investigation of such questions as: "What is the weakest acid that gives a discernible inflection at the endpoint?", or "Can titration be used at arbitraily low concentration levels by using a dilute titrant?", or "Is the inflection point always exactly at the equivalence point?"

Download link: titration.wkz;

Wingz player application and basic set of simulation modules, for windows PCs or Macintosh

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Cell definitions and equations:
Ca Acid conc., M   (cell D2)
Va Acid vol., mL   (cell D2)
Cb Base Conc. ,M   (cell D2)
Ka                 (cell D2)
Kw                 (cell E2)
StartpH            (cell F2)
EndpH              (cell G2)

pH range: StartpH to EndpH in 40 steps
H = 10^-pH
Vb = -Va*((H^3+Ka*H^2-(Kw+Ka*Ca)*H-Kw*Ka)/(H^3+(Ka+Cb)*H^2+(Ka*Cb-Kw)*H-Ka*Kw))

Graph plots Vb on horizontal(x) axis and pH on vertical (y) axis.

(c) 1991, 2000, Prof. Tom O'Haver , Professor Emeritus, The University of Maryland at College Park. Comments, suggestions and questions should be directed to Prof. O'Haver at toh@umd.edu.