A Spectrophotometric Study of the Permanganate–Oxalate Reaction: An Analytical Laboratory Experiment

A spectrophotometric method has been developed to study the classic permanganate–oxalate oxidation–reduction reaction. The experiment is divided into two parts. Part I involves the determination of an unknown oxalate. This part of the experiment not only serves to quantitatively analyze oxalate by following and recording its slow bleaching effect on the absorbance of a measured excess of permanganate over a period of time, but also allows the student (i) to visually follow the course and the rate of the reaction, and (ii) to observe the auto catalytic effect of the reaction product, manganous ion. Part II of the experiment involves examination of the effect of sulfuric acid concentration and the effect of manganous ion concentration on the rate of and outcome of the permanganate–oxalate reaction. The experiment can be completed in two three-hour laboratory periods. The experiment can be modified by excluding Part II and thus be completed in one three-hour laboratory period. The experiment works well in the teaching laboratory and is well received by the students. The experiment intellectually stimulates and challenges the students. It provides the student with experience on the application of the major functions of modern recording UV–vis spectrophotometers and the basics of analytical techniques and stoichiometry calculations.