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Homogeneous photokatalysis in photo-blue-bottle experiments

higher secondary education



V1Color change to blue of the PBB-solution (water based solution with ethylviologen = substrate, proflavine = photokatalyst and EDTA = sacrificial donor) caused by irradiation with light (blue or white light) and reverse color change caused by shaking in a half-filled and sealed testtube
V2PBB in absense of O2 in a fully filled and sealed testtube
V3PBB in an elektrochemical measurement setup consisting of two electrolyte-bridged half-cells with an irradiated and a not irradiated PBB-solution (solar battery with half cells)
V4Compact cell made of FTO glass, filter paper soaked with PBB-Lösung and razor foils (solar battery as compact cell)
V5PBB variations with alternate substrates and photocatalysts

Technical Contents: coupled reaction cycles of the substrate and the photocatalyst, light induced reaction cycle of the photocatalyst, photo electron transfer, redox pairs and their redox potentials in the ground and in the excited state, light energy conversion and storage in the reduced substrate, quantitative determination of the substrtate conversion; relation: structure-color of the colorless and the colored form of the substrate

Scope: cycle of matter (PBB as model experiments for the cycle photosynthesis-cell respiration);
electro chemistry (redox reactions and -potentials, Nernst equation); catalysis (differentiation between photocatalysis and catalysis); energetics (conversion of radiation energy into chemical bond energy) (higher secondary education); chemistry/biology: PBB and carbon cycle in the biosphere

Referenzen

2013
Claudia Bohrmann-Linde; Michael W. Tausch; Frederic Posala; D. Nietz
 
Akku leer? Licht an! - Photoelektrochemische Lichtenergiekonversion und -speicherung
Praxis der Naturwissenschaften - Chemie in der Schule, 63(5)
2007
Michael W. Tausch; Magdalene von Wachtendonk; Claudia Bohrmann-Linde; P. Krollmann; W. Schmitz; J. Wambach
 
CHEMIE 2000+ Gesamtband mit Kompendium für das Abitur
 
Publisher: C.C.Buchner, Bamberg
2001
Silke Korn; Michael W. Tausch
 
A Laboratory Simulation for Coupled Cycles of Photosynthesis and Respiration
Journal of Chemical Education, 78(9):1238
2000
Michael W. Tausch; S. Korn
 
Der Kohlenstoff-Kreislauf bei der Photosynthese und Atmung als Modellexperiment - Gekoppelte Reaktionszyklen
Praxis der Naturwissenschaften - Chemie in der Schule, 49(7):29
1998
D. Wöhrle; Michael W. Tausch; W.-D. Stohrer
 
PHOTOCHEMIE - Konzepte, Methoden, Experimente
 
Publisher: Wiley-VCH, Weinheim
1994
Michael W. Tausch
 
Photo-Blue-Bottle Modellversuche zur Photosynthese und zur Atmung
Praxis der Naturwissenschaften (Chemie), 43(3):13
1989
Michael W. Tausch; D. Wöhrle
 
Photokatalyse
Praxis der Naturwissenschaften (Chemie), 38:37