Abstract:

The use of 3D printing technology enables easy, quick and low cost development of prototypes. This technique is changing teaching in fields such as chemistry, enabling the manufacturing of precise structures based on a digital model. Chemistry is understood by the articulation of three dimensions of knowledge that are related: macroscopic, submicroscopic and representational. The abstract and complex nature of chemical concepts makes it difficult to establish the relationship among these dimensions of knowledge. Through 3D printing it is possible to make the construction of teaching materials that can help students to articulate these three dimensions of chemical knowledge. Polarimeters are equipment used in chemistry laboratories to determine the rotation angle of chiral organic substances, being used in the food, chemical and pharmaceutical industry. This determination allows us to both identify the substance and verify its purity. Two chiral substances are named enantiomers when one of them has a structural formula equal to the mirror image of the other, and they are not overlapping. In the teaching of organic chemistry, especially in the study of stereochemistry, visualization and understanding of the structure of enantiomers, requires students to have a great capacity for abstraction. The use of polarimeters in laboratory classes could help students to understand the relationship between the structure of an enantiomer and its relationship/implication with the deviation of polarized plane light. However, polarimeters are not usually found in school laboratories due to the “high” cost. From this context, our project aims to create a polarimeter for educational use. To make it feasible, the first step consisted of a literature review, to identify the most affordable materials used in the construction of low-cost polarimeters; followed by the identification of the functionality of each one in the polarimeter structure. From these two stages, we conceived a project to create a low-cost educational polarimeter. From the initial stage, the function of each material was identified in each of the three proposals for the construction of a polarimeter [1] [2] [3]. Smartphones and RBG LED diode were used as light sources; beckers and cuvettes - traditional or 3D-printed - as polarimetric tubes; polarizing film and 3D glasses, as polarizers; protractors, polarizing film, document cameras and multimeters, such as analyzers; and 3D printing, Lego bricks and acrylic as the body of the polarimeters. From this information we conceived a new project for the creation of a polarimeter for educational use. For the execution of our project we chose to use a smartphone, polarizing film, 3D printed cuvette and base, and multimeter for the construction of the polarimeter. The next steps in the project are the assembly and use of the polarimeter in organic chemistry laboratory classes.

Acknowledgements:
IFRS, FAPERGS.

References:
[1] P. I. T. THOMPSON. Is That a Polarimeter in Your Pocket? A Zero-Cost, Technology-Enabled Demonstration of Optical Rotation. Journal of Chemical Education, n. 95, v. 5, pp 837-841, 2018.
[2] P. BERNARD; J. D. MENDEZ. Low-Cost 3D-Printed Polarimeter. Journal of Chemical Education, n. 97, v. 4, pp. 1162-1166, 2020.
[3] L. KVITTINGEN. Demonstrating basic properties and application of Polarimetry using a self-constructed polarimeter. Journal of Chemical Education, n. 97, pp. 2196-2202, 2020.

Keywords:

Polarimeter, Chemistry, Laboratory Class.