Oxalate Synthesis and Pyrolysis: A Colorful Introduction to Stoichiometry

Abstract

Metal oxalate synthesis and pyrolysis provides an opportunity for students to (i) learn stoichiometry, (ii) experience the consequences of proper stoichiometric calculations and experimental techniques, and (iii) be introduced to the relevance of chemistry by highlighting oxalates in context, for example, usages and health effects. At our institution, general chemistry students synthesized the hydrated form of either iron(II), nickel(II), or manganese(II) oxalate. Synthesis was followed by oxalate pyrolysis and subsequent determination of the pyrolysis product’s identity, of three possible, using stoichiometric calculations and comparisons of theoretical and actual yields. Striking color changes that accompany these pyrolysis reactions were well received by students and served to highlight the chemical changes involved. Student actual yield values for both the iron and manganese pyrolysis products compared favorably with theoretical yield values and, in addition, 78% and 76% of students would have chosen the correct iron or manganese pyrolysis product, assuming correct stoichiometric and experimental calculations. Flaws in students’ experimental techniques were especially noticeable during pyrolysis of the nickel oxalate. Specifically, students did not heat to constant weight, did not heat to high enough temperature to achieve complete pyrolysis, and ended the pyrolysis prematurely, that is, at an intermediate yellow-colored product.

Microfluidics for Personalized Reactions to Demonstrate Stoichiometry

“…Laboratory exercises have been designed to provide students opportunities to reinforce these concepts and involve one of three methods to visualize stoichiometry. These include reactions that produce a precipitate, , evolve gas, , or result in a color change. , The selection of one of these three approaches for a laboratory exercise is based on the time restrictions for the experiment and the availability of instrumentation. Although a precipitation reaction may be completed quickly, quantification of the precipitate in a laboratory setting is time-consuming because it requires each student to dry and then weigh the precipitate.…”

“…1 Laboratory exercises have been designed to provide students opportunities to reinforce these concepts and involve one of three methods to visualize stoichiometry. These include reactions that produce a precipitate, 3,4 evolve gas, 5,6 or result in a color change. 7,8 The selection of one of these three approaches for a laboratory exercise is based on the time restrictions for the experiment and the availability of instrumentation.…”

All Roads Lead to Rome: Triple Stoichiometry with a Lithium Battery

“…To reinforce its concepts, experiments are continuously designed so that students can better understand molar ratios from a practical standpoint. For example, in the past decade, the Journal of Chemical Education published papers on the subject whereby the favorite techniques to ascertain stoichiometric relationships included mainly colorimetry/spectrophotometry, − conductivity, , electrochemistry, − gravimetry, − titrimetry, , gas generation, − thermochemistry/thermal analysis, , − and catalysis …”

Synthesis and decomposition mechanism of γ-MnC2O4·2H2O rods under non-isothermal and isothermal conditions

“…Therefore, while the mechanism and products of thermal decomposition of the monoclinic dihydrate in air have been extensively studied by various methods [2,3,7,11,17,[26][27][28][29][30][31][32][33][34][35], the literature data for the other two forms are quite scarce. To the best of our knowledge, apart from our studies [18,19], there are only a few papers about MnC 2 O 4 Á3H 2 O [5,9,36,37] and cMnC 2 O 4 Á2H 2 O [11] and they are not always aimed on the investigation of their decomposition mechanism.…”