Determining the activation energy in the school laboratory

Abstract

The paper presents a laboratory experiment carried out with students, which has been cosidered inexpensive and with increased visual impact. The goal was to determine the activation energy of the faze separation process in the water-salt-isopropanol system. The experiment uses low-density polyethylene beads to mark the moment of the chemical equilibrium at the interface between brine solution and isopropanol, at different temperatures. The Arrhenius' equation was then used to find the dependence of the separation process on temperature and the determination of the activation energy of this process. A total of six groups of students carried out this experiment in the school laboratory. The experimental data showed linear graphs of the Arrhenius equation with an outcome of prediction of R2 = 0.93 ± 0.03. The calculated value of the activation energy model was 34.5 ± 2.5 kJ/mol. The reproducibility of the experiment, the simplicity in data collection and analysis and the low cost of the necessary resources makes this laboratory experiment easily adaptable to different education stages from middle school students to high school students, and even to first years of university students.