Figure 1. Color changes during the oxidation of tartaric acid (a: after adding the catalyst, b: green activated complex, c and d: catalyst regeneration)

From

Experiments to Introduce Students into the Temperature Dependence of the Reaction Rate

Marcel Emmert, Konrad Heß, Patrick Gräb, Ekkehard Geidel

World Journal of Chemical Education. 2020, 8(2), 92-99 doi:10.12691/wjce-8-2-5