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Mass Relationships in a Chemical Reaction: Incorporating Additional Graphing Exercises into the Introductory Chemistry Laboratory

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Stephen DeMeo

Department of Curriculum and Instruction, Department of Chemistry, Hunter College of the City University of New York, New York, NY 10021

J. Chem. Educ., 2005, 82 (8), p 1219

DOI: 10.1021/ed082p1219

Publication Date (Web): August 1, 2005

Section:

History, Education, and Documentation

Abstract

The purpose of this article is to increase student involvement with graph construction specifically in the context of introductory laboratory activities that involve mass relationships between reacting substances and products. In this regard, five mass–mass plots derived from a synthesis of a binary compound from its elements are presented as well as a set of questions to focus learners on the significance of each plot. The benefit of providing learners with these types of graphing activities include the use of higher-order cognitive processes as well as the elucidation of fundamental chemical knowledge such as the law of the conservation of mass, the law of constant composition, limiting and excess reactants, and empirical formula. To incorporate graphing exercises involving mass relationships into lab activities, three simple actions are necessary: (i) the quantities of reactants that have undergone transformation and the quantities of products that have been made as a result of the chemical reaction must be directly measured or deduced, (ii) the mass of reactants in the experiment must be varied, and (iii) to save time, students should work in groups and pool data.