TY  - JOUR
A1  - Emmert, Marcel
A1  - Heß, Konrad
A1  - Gräb, Patrick
A1  - Geidel, Ekkehard
T1  - Experiments to Introduce Students into the Temperature Dependence of the Reaction Rate
JF  - World Journal of Chemical Education
N2  - It is a challenge in chemical education to understand basic principles of chemical reaction kinetics on an experimental basis because of the relatively extensive experimental setup and the often time-consuming measurement series. This contribution offers an introduction into the field of the temperature dependence of reaction rate with easy-to-use experiments. Data logging systems have been used to get sufficient data-sets to evaluate different measurements in reaction kinetics. Several experiments were designed for practical courses in chemistry, which allow students to derive the simple van‘t Hoff rule on the one hand. On the other hand, the Arrhenius equation can only be derived on the basis of experimental data with the help of information from collision theory and Maxwell-Boltzmann distribution.
KW  - temperature dependence of reaction rate
KW  - van‘t Hoff rule
KW  - Arrhenius equation
KW  - ow-cost photometer
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-229993
VL  - 8
IS  - 2
ER  - 
TY  - JOUR
A1  - Gräb, Patrick
A1  - Geidel, Ekkehard
T1  - Spectroscopic studies of food colorings
JF  - World Journal of Chemical Education
N2  - In chemical education, it is often a challenge to understand the basic principles of spectroscopic techniques due to missing connections to the real world. Therefore, the present contribution offers context-based applications of UV/Vis spectroscopy for analytics of food colorings with which learners can improve their skills regarding this method. The spectroscopic determination of food colorings seems to be a promising approach due to the long tradition and omnipresence of dyes in supermarket products. The therefor-required spectral data for commonly used dyes are provided for educational usage. Qualitative and quantitative analytics of food colorings in four different lemonades and chocolate beans have been used to introduce learners to important analytical techniques like sample preparation or elimination of confounding factors. These analytics also display the limitations of the method in the visible range of light in the case of tartrazine and curcumin. By applying Lambert-Beer-Bouguer’s Law in different variations, typical calculations of concentrations can be studied in quantitative analyses. The studied food samples demonstrate the different usage of food colorings depending on the country of sale. Finally, a 3D-printable low-cost photometer suitable for the discussed quantitative analytics in educational contexts is presented.
KW  - UV/Vis spectroscopy
KW  - quantitative analysis
KW  - food colorings
KW  - context-based teaching
KW  - low-cost photometer
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-201908
VL  - 7
IS  - 2
ER  -