Conductimetric Titrations: A Predict−Observe−Explain Activity for General Chemistry

Abstract

A predict−observe−explain framework is used to explore conductimetric titrations of a hydrochloric acid−sodium hydroxide (strong acid−strong base) and an acetic acid−sodium hydroxide (weak acid−strong base) system in which all components are soluble. In the strong acid−strong base system, the conductivity decreases as the titration progresses to the equivalence point and then increases past the equivalence point. In the weak acid−strong base system, the conductivity increases as the titration progressed to the equivalence point and then increases at a greater rate past the equivalence point. In another more sensitive titration of the weak acid−strong base system, the conductivity initially decreases slightly, then increases as the titration progresses to the equivalence point, and then increases at a greater rate past the equivalence point. These characteristic conductimetric titration curves are analyzed and explained.