Development of small-scale and low-cost galvanic cells as a teaching tool for high school student

In this work consists of two parts. In the first part a simple method for the fabrication of small-scale and low-cost galvanic cells was developed as a teaching tool for electrochemistry of high school students. The method was designed according to the concept of “Green chemistry” reducing use of chemicals, less waste generation, and time consumption while retaining the experimental concepts. In this work, these galvanic cells contain various electrodes, including Cu, Zn, Al, Mg and Fe and a low cost salt bridge which was made from a cotton thread (with the length of 9 am) soaked with electrolyte solutions. Our experimental setup corresponded to the conventional platform; however, herein using much less electrolyte volume (2.00 mL). The cells were studied for the optimum conditions including concentration of electrolyte of each cell (0.01 M), the solutions employed as salt bridge (0.01M KNO3) as well as the study of reagent lifetime of electrolyte (720 h). The results obtained from the constructed galvanic cell were in agreement with those obtained from the conventional method considering by the t-test (tstat=2.414, tcrictical=2.447) at p value of 0.05. in the second part, the application of developed small-scale was implemented based on 5E inquiry learning approach to enhance students’ conceptual understanding of electrochemistry. The research tools consisted of four small-scale experiments involving electrochemistry, which was oxidation and reduction reactions, galvanic cells, cathodic protection of iron nails, and connecting batteries in series. The data collecting tools included 1) a conceptual test of electrochemistry and 2) the mental model drawing of a galvanic cell. Twenty-eight Grade 12 students participated in the series of four 5E learning activities for a total of 10 hours. Paired samples T-test analysis revealed that the mean scores of the post-conceptual test (mean 38.29, SD 5.62) was statistically higher than that of the pre-conceptual test (mean 19.29, SD 5.43) at p value of 0.05. In addition, the mean scores of the post-mental models in both the macroscopic (mean 3.82, SD 0.55) and sub-microscopic features (mean 4.75, SD 1.23) were statistically higher than those of the pre-mental models (mean 1.68, SD 1.32 and mean 1.18, SD 1.50) at p value of 0.05. Prior to intervention, most students were in the categories of less correct conceptions, Partial Understanding with specific Mis –understanding (PMU) to No Understanding (NU). However, after the intervention, they moved to the categories of more correct conceptions, Partial Understanding (PU) to Sound Understanding (SU). This indicated that this intervention can enhance students’ conceptual understanding of electrochemistry and mental models of galvanic cells.