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The Chemical Educator
ISSN: 1430-4171 (electronic version)
Abstract Volume 19
(2014) pp 153-156
An Alternative Approach to Titrating Fe2+(aq) in Dietary Supplement Tablets Using Electrolytically Produced Ce4+(aq)
Huirui Washington, Christopher Scanlon, Samuel Melaku, James O. Schreck, and Rajeev B. Dabke*
Department of Chemistry, Columbus State University, Columbus, Georgia 31907, dabke_rajeev@columbusstate.edu
Received January 6, 2014. Accepted May 21, 2014.
Published: 30 May 2014
Abstract. An alternative method in an undergraduate laboratory experiment for the volumetric titration of iron in dietary supplement tablets is presented. Ce4+(aq) was produced by anodic oxidation of Ce3+(aq) in acid solution, and Fe2+(aq) was titrated against electrolytically produced Ce4+(aq). The progress of the titration was monitored either by visual color change of ferroin indicator or by the potentiometric method. The amount of electrolytically produced Ce4+(aq) was determined by measuring the volume of H2(g) produced at the cathode. The experimental method presented in this paper offers the advantage of a coulometric method while eliminating the requirement of an expensive coulometer. The average mass of iron in the dietary supplement tablet was 64 mg agreeing with the potentiometric titration results (63 mg), manufacturer’s label (65 mg), and the independent volumetric titration (66 mg).
Key Words: Laboratories and Demonstrations; analytical chemistry; electrolytic reactions; redox reactions; potentiometry; perfect gas law; stoichiometry
(*) Corresponding author. (E-mail: dabke_rajeev@columbusstate.edu)
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