RSUSSH 2020
IN20-200 Assessing Students’ Conceptual Understanding of the Relationship between Solubility and Polarity of Organic Compounds
Presenter: Aphiwat Ratriphruek
Mahidol University, Nakhon pathom
Abstract
Solubility and polarity of organic compounds are the important principles of organic chemistry. These fundamental concepts are used for introducing solvent selection for purification, as well as analysis techniques, etc. Therefore, these topics are important for students to learn, however, in the past polarity and solubility have been reported as difficult topics for students to learn. So, knowing how students’ understanding or misconceptions of these concepts will be useful information for developing activities to enhance students’ learning the concept. This study investigates how students understand the relationship between solubility and polarity during the extraction of plant pigments by various solvents. High school students who already learned the concept of solubility, polarity, and covalent bonds were chosen for this study. The extraction activity was set up for students to perform in each group, after finishing the laboratory activity students were asked to complete opened-ended questions and interview to explain how the plant pigment can be extracted by solvents. The students’ answers were analyzed using thematic analysis and their explanation was categorized into groups based on the feature that included in the explanation. The results showed that only 50 percent of students answer correctly by link the effect of the solvent polarity and plant pigment to explain the solubility during the extraction. However, their answers still lack the explanation about intermolecular force between solvent and solute. While students (50 percent) have a partial understanding of these concepts since they provided the explanation with the alternative conception. In conclusion, although students have already learned the concept of polarity and solubility, some of them could not link the concept of polarity and solubility and they also hold some alternative concepts.
Citation format:
Ratriphruek, A., & Chenprakhon, P.. (2020). Assessing Students’ Conceptual Understanding of the Relationship between Solubility and Polarity of Organic Compounds. Proceeding in RSU International Research Conference, May 1, 2020. Pathum Thani, Thailand.QUESTIONS & ANSWERS
1. Why do you use the small sample size?
2. This study aims to assess students’ conceptual understanding of solubility and polarity of organic compounds using plant pigment extraction process in order to investigate the relationship between solubility and polarity of compound. However, the student answers still lack the explanation about intermolecular force between solvent and solute. What do you think about this?
According to your studies, you stated that students thought that the dissolving process is related to chemical reactions. what do you think why students hold this misconception ?
Dear ผศ.ดร.อรจิรา อารักษ์สกุลวงศ์
Ans 1 The sample size is too small since the study is administered during the semester-break; therefore, the enrolled participants were the volunteer students who are willing to participate in the activity.
Ans 2 To explain dissolving process, intermolecular forces between solute and solvent are the main factors that affect the solubility of solute. From students answer, it might be due to learning this concept does not emphasize the interaction between solvents and solutes, so that make students do not perceive the relevance of intermolecular force during the dissolving process.
Thank you very much for your questions.
Dear กฤษกร บุญประเสริฐ
Base on my study, I think students have the alternativeconception about the separation of chemical reaction and physical process. Color change is the one of evidence for chemical change, they may confuse about change of solvent color (from clear to colored). Therefore, students stated that the extraction of pigment involve chemical change.
Thank you very much for your questions
Dear, presenter
first of all, your research is very interesting. but I have a question about extraction activity. Did you explain the chemicle compounds in plant pigments to students or not in order to let them know about polarity of plant pigments ? I'm not sure about that but I think in plant pigments may have both polar and nonpolar part that might be confusing for students about solubillity. What do you think about this?
Dear แพรวสุภา เหล่าศิริ
Answer 1 The laboratory activity allows students to investigate the solubility of plant pigment in various solvents. Students were assigned to carry out the solvent extraction experiment using different polarities of pigments. We provided students the laboratory worksheet which have the infomation about pigment structures and polarities of solvent.
Anwer 2
This study we select the solvents whic have various polarities (water, ethanol,2-propanol,acetone,and hexane), so the order of solvent polarities could help students to distinguish the polarities of plant pigments. For example, Chlorophyll have both polar and nonpolar part that mean it would have low solubilitty in water but it would have high solubility using ethanol or 2-propanol.
Thank you very much for your questions