Stoichiometry and Limiting Reactants Activity

Authors

Abstract

This activity aims to develop students understanding of limiting reactant stoichiometry at the particulate level in addition to manipulating reaction stoichiometric amounts mathematically. The activity starts with a sticky note activity building and reacting molecules until no further products can be formed. Students discover that although they started with a 1:1 reactant system, not all of the reactants could be used to form products. Students are asked to apply and define the following terms: make/produce/yield, use, excess, and limit. Students then relate the balanced chemical equation to the amounts that reacted in the sticky note exercise. The intent is to get students to define a balanced equation in terms of ideal, lowest whole number ratio of reactant to products instead of trying to rewrite a balanced equation based on actual amounts used in a reaction. Students work through molecule to molecule and mole to mole relationships in a reaction with excess reactants, once again requiring them to apply the earlier defined terms. Students then are guided to calculate amounts in a reaction with excess reactant to discover that conservation of mass is still followed although some of the mass is still as unreacted reactant. The final part of this activity applies these concepts by starting with gram amounts of reactants but once again asks students to apply the earlier defined terms.

Level: Undergraduate or Advanced High School
Setting: Classroom
Activity Type:  Learning Cycle
Discipline: Chemistry
Course: General Chemistry
Keywords: balanced chemical equations, stoichiometry, particulate nature of matter

Author Biographies

Abdi-Rizak M. Warfa, University of Minnesota

Abdi is assistant professor of biology teaching and learning at the University of Minnesota where his group conducts interdisciplinary research that blends aspects of biology, educational theory, cognitive science, and educational research methodologies to improve the teaching and learning of biological sciences at the undergraduate level. Most recently, his group conducted studies that examine the nature of classroom interactions and how students learn and reason in the context of active learning classrooms. He is also interested in research methodologies as they pertain to undergraduate STEM education research. Before getting interested in the learning sciences, Abdi studied biochemical pathways in malaria parasites, specifically the thymidylate synthase pathway. He did his undergraduate studies in biochemistry and chemistry at UC San Diego, graduate studies in chemical biology at the UW Seattle, and Chemical Education at the University of Minnesota.

James M. Nyachwaya, North Dakota State University

James Nyachwaya is associate professor of Chemistry/Biochemistry and Science Education at North Dakota State University. His research focuses on students’ conceptual understanding of the particulate nature of matter. He also studies chemistry curriculum, looking at the nature and use of representations in textbooks.

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Published

2021-01-29

How to Cite

Schneider, J. L., Abdi-Rizak M. Warfa, & James M. Nyachwaya. (2021). Stoichiometry and Limiting Reactants Activity. POGIL Activity Clearinghouse, 2(1). Retrieved from https://pac.pogil.org/index.php/pac/article/view/148

Issue

Vol. 2 No. 1 (2021)

Section

Activities for Review

License

Copyright of this work and the permissions granted to users of the PAC are defined in the PAC Activity User License.