Optimizing Low-Cost Educational Calorimeters: A Quantitative Analysis of Experimental Uncertainty

This study systematically investigates the factors that influence the performance of three low-cost, homemade calorimeters─a Dewar flask, a 180 mL polystyrene cup, and a 50 mL polystyrene cup─through the analysis of their thermal insulation, calorimeter constant, and measurement uncertainties in determining the solution enthalpies of NaOH and KCl. Error propagation analysis demonstrates that the most critical parameter for improving reproducibility is the appropriate selection of the water-to-analyte mass ratio. The measurement of temperature variation emerges as the primary source of uncertainty, whereas thermal insulation becomes relevant only when the temperature change is small, and the contribution of the calorimeter constant to the total uncertainty is limited or even negligible in most cases. By intentionally designing experiments under conditions that yield different levels of error, this work provides a framework that enables students to identify the predominant sources of experimental uncertainty. More broadly, this approach promotes the development of students’ skills in data analysis and scientific interpretation, while also offering chemistry educators a model for incorporating an error-focused perspective into laboratory instruction.