Acid–base knowledge and skills are needed in almost every aspect of organic chemistry. We used that required knowledge and skills to design a series of learning outcomes for organic acid–base chemistry, organized in a gradient of difficulty in the graphic below (1).
We designed this acid–base learning module as part of OrgChem101, based on our previous work in learning outcomes for acid–base chemistry and students’ challenges and learning opportunities (1, 2).
Within the OrgChem101.com modules, students watch videos, practice questions, and receive feedback. The module is aligned with the acid–base learning outcomes above, and has a metacognition skill-building layer (Get Started and Wrap Up sections).
Each section of the module is informed by known student difficulties. For example, students can struggle with the information literacy skill of identifying and estimating pKa values (2). That skill is explicitly explained in the module, with opportunities for practice and feedback.
Students’ estimates of pKa values (2).
Students can be asked to compare and justify relative acidity/basicity in a number of contexts or by integrating their knowledge (see graphic). They can also be asked to do so at different levels of granularity (e.g., experimentally determined pKa values or chemical factors/reasoning). They can also be asked to give various levels of reasoning in their answers. For example, with descriptive reasoning, they might state that the weaker acid has the higher pKa value, without expanding on the reasons why. Alternatively, they could use causal reasoning to explain how factors such as electronegativity, resonance, or hybridization stabilize certain bases more than others. In the example below, students could choose the desired level of granularity and the type of reasoning required was not specified. Most used pKa values (58%) and relational (48%) or linear causal (28%) reasoning, describing the connection between pKa values and conjugate base strength (n = 170) (3).
Modes of reasoning for students’ arguments for Question 1, above (incorrect claims, n = 60; correct claims, n = 110) (3).
When competing factors are present, students may be asked to justify their answer using pKa data, or a combination of pKa data and chemical factors. An example is shown below (3).
This question type asks students to systematically analyze each factor that could stabilize/destabilize a given species, then use experimental data (pKa values) to draw a conclusion, and explain their answers through scientific argumentation (3).
DATA SOURCES
This project was realized through a collaboration with the Centre for eLearning—part of uOttawa’s Teaching and Learning Support Service—and senior undergraduate student Melissa Daviau-Duguay. Our posters from the Canadian Network for Innovation in Education conference (Chem_Poster_CNIE FINAL.pdf) and the International Conference in Chemical Education (Nomenclature101_Poster_ICCE.pdf) explain more.
Nomenclature101.com team: Gisèle Richard, Richard Pinet, Alison Flynn, Melissa Daviau-Duguay, Caroline Marcoux, Jeanette Caron, Jamey Laroche
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References
Stoyanovich, C.; Gandhi, A.; & Flynn, A. B. “Acid-Base Learning Outcomes for Students in an Introductory Organic Chemistry Course.” Journal of Chemical Education, 2015, 92 (2), 220–229. doi.org/10.1021/ed5003338.
Flynn, A. B. & Amellal, D. G. “Chemical Information Literacy: pKa Values--Where Do Students Go Wrong?” Journal of Chemical Education, 2016, 93 (1): 39–45. pubs.acs.org/doi/abs/10.1021/acs.jchemed.5b00420.
Deng, J. M. & Flynn, A. B. “Reasoning, granularity, and comparisons in students’ arguments on two organic chemistry items”, 2021, Chemistry Education Research and Practice, Accepted doi.org/10.1039/D0RP00320D.