Abstract

CATALDO, Fernando; ARRIAGADA, Sebastián  and  HERNANDEZ, Diógenes. Batteries, an experimental form of teaching of redox processes. Educ. quím [online]. 2019, vol.30, n.3, pp.24-33.  Epub Nov 30, 2019. ISSN 0187-893X.  https://doi.org/10.22201/fq.18708404e.2019.3.68309.

In the teaching of an experimental science such as chemistry, it is essential to have experiments that connect theory with reality. Our work consisted of developing experiments for the Oxide-Reduction unit using combinations of commonly used metals and some pure metals. With these we manufacture galvanic cells, where several of them did not adjust to the theoretical potentials (table of reduction potentials), mainly iron, aluminum and magnesium, either by being in the form of alloys or by forming oxide layers that altered these values. Measuring the voltage of a battery with a voltmeter does not show the student the actual generation of current, that is why our experiment aimed to light some 1.6V and 5 mA LEDs. The manufacture of batteries with the adequate voltage was not enough to light these LEDs, which was solved using 2 to 4 saline bridges, with what the students could visualize the importance of these in charge compensation and current intensity. To visualize the corrosion process, the design of the galvanic cell was modified, introducing both metals in a single container with a solution of sodium chloride and it was observed that the higher the concentration of this salt, the higher the current intensity (managing to turn on the led), as well as corrosion of the anode electrode.

Keywords : galvanic cells; oxide reduction; chemistry experiments; saline bridges; corrosion.

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