6. Buffer Solutions and Polyprotic Acids

  1. Brian M. Tissue

Published Online: 7 JUN 2013

DOI: 10.1002/9781118647042.ch6

Basics of Analytical Chemistry and Chemical Equilibria

Basics of Analytical Chemistry and Chemical Equilibria

How to Cite

Tissue, B. M. (2013) Buffer Solutions and Polyprotic Acids, in Basics of Analytical Chemistry and Chemical Equilibria, John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9781118647042.ch6

Author Information

  1. Virginia Tech, Department of Chemistry, Blacksburg, VA, USA

Publication History

  1. Published Online: 7 JUN 2013
  2. Published Print: 12 JUL 2013

ISBN Information

Print ISBN: 9780470592083

Online ISBN: 9781118647042



  • acid–base buffer systems;
  • alpha fraction plots;
  • buffer solutions;
  • polyprotic acids;
  • weak acid titration curve


This chapter describes polyprotic acid and develops an understanding of acid–base buffer systems. There are three cases for predicting p[H3O+] with polyprotic acids: end cases (only a weak acid or a weak base); a buffer system (a weak acid and its conjugate base); and amphiprotic species. The three cases each have an appropriate approach for predicting p[H3O+]. The chapter also introduces alpha fraction plots, which provide a graphical means of visualizing the different forms of polyprotic acids as a function of pH. Weak acids and weak bases have titration curves that are slightly different, which can provide additional qualitative information about the acid–base system. This information is most useful when trying to identify an unknown acid.