Skip to main content
Chemistry LibreTexts

Background

The research team that created and assessed the chemical equilibrium module at Wright State University, Central State University and University of Dayton was part of the Ohio Higher Education Network (OHEN) sponsored by State of Ohio funding. Individuals working on the OHEN were to promote change in the instruction of undergraduate science courses, especially those taken by pre-education teachers, and to enhance students’ understanding of science concepts. The research team for this OHEN project included faculty members from the Department of Chemistry at Wright State University, the Water Resources Department at Central State University, and the Geology Department at University of Dayton. Such an interdisciplinary team was designed to provide pre-service teachers taking chemistry multiple perspectives in the inquiry-based lesson that would integrate water quality and geology concepts. This particular chemistry inquiry lesson was developed as part of a required chemistry course for Middle Childhood Education undergraduate pre-service teachers and graduate students majoring in Interdisciplinary Master of Science in Teaching. Content knowledge built in an inquiry-based mode includes heat and temperature, kinetics, equilibrium, acids and bases, electrochemistry, and organic chemistry. The mathematics prerequisite is Fundamental Mathematics Concepts which includes basic college arithmetic, algebra, and trigonometry. The purpose of the course is to prepare pre-service teachers who may currently lack skills to train their future students to attain process skills necessary to satisfy the national and state standards and also to face global competition in science achievement. This course also prepares science teachers to teach concepts in chemistry as applied to real world problems using a cross-disciplinary approach. The chemical equilibrium chapter was used to investigate teaching chemistry by choosing examples across disciplines. Accordingly, this chapter was taught using water quality as an example on a backdrop of a river and a geologic out crop. Students are not required to be experts in geology or water quality. The basic concepts of water quality and geology required are introduced to the pre-service education teachers/students during the field trip. The chapter included definition of equilibrium, equilibrium constant, homogenous and heterogeneous reaction equilibrium, Henry’s law, law of mass action and solubility product. We will discuss the evaluation technique that was used to determine how the integrated approach affected the student’s conceptual understanding of chemical equilibrium (5).

Our teaching method included: 1) a field trip to the Huffman Dam along the Mad River, Dayton, Ohio 2) having students make observations of the environment around them with such questions asked as: What rock observed by the bedrock provides calcium in water?; What is limestone and do you find any at the Huffman Dam?; How do these minerals affect the chemical composition of water near the bedrock and water that runs off into the Mad River?; How does the fertilizer applied on the Mad River watershed affect the quality of water in the river? 3) Prompting students to use their observations to develop scientific hypotheses and make measurements of pH, dissolved oxygen, temperature, turbidity, concentration of phosphates, nitrates and carbonates, upstream and downstream of Huffman Dam. In the field, pre-education students also collect samples of rocks, soil and fossils in addition to measuring the water quality parameters such as pH of the water and soil. In the laboratory, students measured total hardness and also calcium hardness in the samples collected from the field trip (4), providing students an opportunity to construct their knowledge by working through an inquiry packet on chemical equilibrium. The inquiry packet, included in the Teacher’s Guide provided as supplement to this manuscript, was designed to associate the measurements made both in the field and the laboratory with concepts on chemical equilibrium. Measurements such as pH and dissolved oxygen were compared with predictions of these parameters using theory of chemical equilibrium. Concentrations of phosphorus and calcium were measured both in the field using Hach instruments and in the laboratory. These measurements were compared with predictions assuming these ions are in equilibrium with minerals such as limestone and dolomite present in rocks and soil in this region. Thus, the concept of chemical equilibrium was reinforced through proper integration of chemistry, quality of natural water in the river, and dissolution of rocks and minerals in soil. Such an integration was accomplished through the involvement of instructors from Chemistry education, Water Resources and Geology (5.) During the field trip, students were actively working as scientists rather than having them read about or listen to lectures about what has been found at Huffman Dam. Students conducted scientific work by making observations on the river near the Huffman Dam, developing hypotheses that water quality can be predicted using equilibrium chemistry and testing their hypothesis. The role of an instructor is to assist student exploration and discovery by providing opportunities for them to make observations. This OHEN approach motivates future teachers to teach science as a process by incorporating similar teaching approaches in their science classrooms (7-9). In order to assess this new approach using a combination of lab and field experiences, instructors compared the inquiry method with traditional lecture methods. The lecture method involved covering the chapter on Chemical Equilibrium from the prescribed textbook. Students were taught in the traditional lecture mode first and then the guided inquiry method. The same pre-test and post-test were administered for both methods of instruction.