Titration curves polyfunctional acids

The derivation of a titration curve for a polyfunctional base is similar to the previous one for acid. 

This chapter describes polyfunctional acid and base systems, including buffer solutions. Calculations of pH and titration curves are also described. 

The pH of polyfunctional systems, such as phosphoric acid or sodium carbonate, can be computed rigorously through use of the systematic approach to multiequilibrium problems described in Chapter 11. Solution of the several simultaneous equations that are involved is difficult and time consuming, however. Fortunately, simplifying assumptions can be invoked when the successive equilibrium constants for the acid (or base) differ by a factor of about 10 (or more). With one exception, these assumptions make it possible to compute pH data for titration curves by the techniques we have discussed in earlier chapters. 

Spreadsheet Summary In Chapter 8 of Applications of Microsoft Excel in Analytical Cheniistiy, we extend the treatment of neutralization titration curves to polyfunctional acids. Both a stoichiometric approach and a master equation approach are used for the titration of maleic acid with sodium hydroxide. 

The construction of a titration curve for a polyfunctional base involves no new principles. To illustrate, consider the titration of a sodium carbonate solution with standard hydrochloric acid. The important equilibrium constants are... 

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