Determination of Sulfate by Conductometric Titration: An Undergraduate Laboratory Experiment

Abstract

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.

Determination of Titratable Acidity in Wine Using Potentiometric, Conductometric, and Photometric Methods

“…The laboratory in the United States also simultaneously monitored solution conductivity as the titration progressed, and a sample conductometric titration curve is shown in Figure . The shape of these was markedly different from that observed in simpler systems, such as sulfates or strong acids, , and similar to those for mixtures of weak acids, such as wines, as reported by Darius-Martin et al The equivalence point is represented by the intersection of the first two trendlines, which represent titration of the tartaric and malic acids. The dilution correction factor recommended for most applications could not be effectively applied because of the volume changes introduced by sample removal for photometric analysis, which also resulted in irregular trendlines.…”

Rethinking a Timeless Titration Experimental Setup through Automation and Open-Source Robotic Technology: Making Titration Accessible for Students of All Abilities

“…While this system only addresses the titration aspects of the experiment, assistance is still required for equipment setup, volume measurements, and dilution. Furthermore, with a few modifications it is possible to adapt this titration setup to other undergraduate experiments, such as potentiometric titration, conductometric titration, and complexometric titration. − For example, conductometric titration can be performed via connecting a conductivity electrode to the analog port of the Arduino . As for potentiometric titration, construction of a potentiostat is required, and instructions for this can be found elsewhere .…”

“…16−19 For example, conductometric titration can be performed via connecting a conductivity electrode to the analog port of the Arduino. 19 As for potentiometric titration, construction of a potentiostat is required, and instructions for this can be found elsewhere. 20 Therefore, this automation approach removes most of the unnecessary physical barriers to learning for students with disabilities.…”

Intersecting Straight Lines: Titrimetric Applications

“…The general fundamentals of this technique are collected in Gelhaus and Lacourse (2005) [74] and Gzybkoski (2002) [75]. Its importance in the educational literature has been highlighted [76,77] and many examples have been recently published in the Journal of Chemical Education i.e., studies on sulfate determination [78]; the identification and quantification of an unknown acid [79], electrolyte polymers [80,81], acid and basic constants determinations [82], its use in general chemistry [83], microcomputer interface [84] and conductometric-potentiometric titrations [85]. An accurate method of determining conductivity in acid-base reactions [86], the acid-base properties of weak electrolytes [87], and those of polybasic organic acids [88] have also been recently subject of s tu dy.…”