Determination of Sulfate by Conductometric Titration: An Undergraduate Laboratory Experiment

The classic technique for sulfate analysis in an undergraduate quantitative analysis lab involves precipitation as the barium salt with barium chloride, collection of the precipitate by gravity filtration using ashless filter paper, and removal of the filter paper by charring over a Bunsen burner. The entire process is time-consuming, hazardous, and frequently yields poor results. Titrimetric methods are much faster, but a good indicator has not been found for sulfate titrations. However, because the relative concentrations of ions in solution change during a titration sequence, monitoring conductivity during the progress of a titration produces a signal which can be used to indicate the equivalence point. A conductometric titration protocol has been developed which is relatively rapid, inexpensive, and can produce results as accurate as the classic technique in an undergraduate laboratory.