Finally! The chance to experiment, to stand in a real university lab and conduct experiments for ourselves - that's what school students involved in the Elite Academy for Chemistry and Materials Science [de] were thinking as they traveled to the Fehling Lab in Stuttgart on February 15 and 16, 2022, for an afternoon of experimentation for school students. If you had asked them who "Fehling" was, many would certainly have answered that he developed the Fehling solution test for detecting aldehydes and ketone sugars. But Hermann von Fehling was also an important figure for the University of Stuttgart - he helped the "vereinigte Real- und Gewerbeschule in Stuttgart" become first a polytechnic school, and then a technical university in 1876. This then went on to become the University of Stuttgart. However, his commitment to ensuring that students received a thorough, practical education was of course unknown to the Elite Academy participants. So, who better to name an experimental student laboratory after at the University of Stuttgart?
The focus of this afternoon of experimentation was acid-base titration, and many students were already aware of how to recognize the end point of such a titration: "You need an indicator!" was the unanimous opinion. Therefore, the first step was to try out which colorations are shown by different indicators in acidic, neutral and alkaline environments. The first neutralization was performed by conducting a preliminary test. In a small Petri dish, students added water and a few drops of universal indicator solution and then added a spatula tip of citric acid and soda ash, respectively, to opposite sides of the dish at the same time. While the addition of citric acid resulted in a red coloration, a blue coloration was observed with soda ash. Finally, the acidic and alkaline solutions met in the middle. At this point, the neutralization process was shown by yellow coloration, as well as the release of CO2 by the formation of gas bubbles.
The next step was to conduct the first real titration of hydrochloric acid with sodium hydroxide solution. To carry this out correctly, the participants first received instruction on how to properly use a burette. How do I fill the volumetric solution exactly to the zero point? How do I read the measurement correctly? These issues had to be clarified first, to ensure that the students were able to work accurately. The experiment also involved working with a volumetric pipette and Peleus Ball. After titration had been carried out, the participants compared their results and calculated the concentration of hydrochloric acid together. In a further titration experiment, the school students determined whether the concentration of acetic acid on a bottle of conventional household vinegar was correct.
Not only the participants, but also the supervising teachers were enthusiastic: "Finally, the chance to experiment in-person with a big group, I have really missed that over the last two years. And it’s a really great, motivated group!"
Special thanks go to Dr. Marco Spurk, the managing director of the Fehling Lab, as well as the supervising teachers, Ms. Frank, Ms. Leuthner, Ms. Paparone, Ms. Pilz and Ms. Rambach for the successful afternoon of experiments. The Elite Academy for Chemistry and Materials Science is part of the School for Talents at the University of Stuttgart.