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Abstracts PdN-ChiS 6/61 Determination of caffeine – a measuring experiment from doping analysis B. Krüger, M.W. Tausch Carrying out a doping analysis requires care, accuracy and a theoretical understanding. These competences can be learned and practised when experimentally determining the concentration of caffeine as proposed in this article. PdN-ChiS 6/61, p.5 Cleaning systems for contact lenses – didactical potential I. Bentlage, H. Kleinhorst. K. Sommer Two different peroxide systems for cleaning contact lenses serve as cause for dealing with the topic catalysis. The experiments described are suitable for teaching chemistry in different grades. PdN-ChiS 6/61, p.8 Take care of the pence and the pounds will take care of themselves? – archaeometallurgy of medieval money in the context of history and sciences R. Lehmann, C. Vogt In a framework of a project involving material analysts, mineralogists, archaeologists, and numismatics diverse forms of means of payments were investigated. The main topic was a better reconstruction of medieval silver trade routes in Germany. Analyses show that silver for bars mainly originates from the Harz region and that silver bars were traded in the most important European trade centers such as the Champagne, Florence and Venice. These results point out the importance of the Harz as dominating supplier of non-ferrous metals for the whole of central Europe. Silver mines in the Harz had a decisive economic importance in medieval times. Access to the silver mines meant control over the silver circle throughout the entire Holy Roman Empire. It was fought over by the Duke of the Guelphs Henry the Lion and the Emperor Friedrich Barbarossa. PdN-ChiS 6/61, p.13 Enfleurage á froid – a pupil-oriented method of gaining scents illustrated by excerpts from the film “Perfume – the story of a murderer” I. Rubner, U. Bau, M.Oetken, J. Friedrich Using excerpts from the film “Perfume – the story of a murderer” the method of enfleurage á froid is experimentally carried out in the classroom and different methods of separating matter are acquired. PdN-ChiS 6/61, p.21 Rose scent – chemical description of molecules in scents A. Mannschreck, E. von Angerer The distillation of rose petals with water yields costly rose oils, which contain most scents from the petals. Steam distillation is carried out in an industrial scale. On a quantitative basis, the most important fragrant substances in rose petals are 2-phenylethanol, (S)-citronellol, geraniol and nerol. The quantities of β–ionon and β–damascon are very small, but they have a surprisingly great influence on rose scent. The molecular structures of these substances are suitable for introducing the following types of isomers: constitution isomers, enantiomers because of the tetreaedric C-atom and diastereomers because of the C-C bond. Gas chromatography can be used for separating scents and in combination with mass spectrometry for identification. The connection of rose scent with chemistry is described. The contents of the article aim at chemistry in Sekundarstufe II. PdN-ChiS 6/61, p. 28
Really attractive – investigation of the magnetic character of complex compounds C. Hoffmann, S. Mika, R. Herbst-Irmer, E. Irmer, T. Waitz The article describes how paramagnetism of complex compounds can be investigated using a neodym magnete. A teaching sequence is proposed in which starting from the phenomenon of paramagnetism the ligand field theory is introduced. PdN-ChiS 6/61, p. 31 The reaction of sodium metal with water – a classic school experiment in a new outfit H. Brandl, E. Mittmann The reaction of sodium with water is not carried out using phenolphthaleine as indicator, but a natural fluorescence indicator (extract of Narra wood) or with luminal as chemoluminescence indicator. In the dark the formation of sodium hydroxide solution can be observed due to the fascinating glowing traces which occur. PdN-ChiS 6/61, p.36 Teamteaching – a chance for teaching chemistry the experiment-based way and for practice-oriented teacher training T. Waitz, K. Riehm, E. Irmer Students training to become chemistry teachers at the University of Göttingen can do their second practical training within the project “teamteaching” at the Otto-Hahn-Gymnasium. Doing this they are in the classroom as “assistant teacher”, additionally to the regular teacher. Together with the regular teacher they plan lessons and help out in experimental or practice phases. PdN-ChiS 6/61, p.39 An experiment on conductivity titration – calculating the molar conductivity, concentration and conductivity T. Teetz Conductivity titrations are mainly used for determining the concentration of a substance in a solution. By calculating the theoretical conductivity with a calculation program and by comparing the results with the experimentally gained data, it becomes possible to understand a precipitation titration and other reactions based on their mechanisms. This is demonstrated using the example of the precipitation titration of sulfate-ions with barium chloride solution. PdN-ChiS 6/61, p.43 Thermodynamics – a jumbled letters riddle J. Hermanns, L. Fuchs, L. Neumeyer, R. Schalinski, L. Schottstädt Chemical energy, educt and 14 other terms on the topic thermodynamics have to be found in the proposed riddle. PdN-ChiS 6/61, p.47
I n f o r m a t i o n s m a t e r i a l v o m 1 7 . 0 1 . 2 0 0 8 Zysten, Fisteln und Co. Der 18. November 1686 war der aufregendste Tag im Leben des Chirurgen Charles- François Félix (1653-1703). Ein Jahr lang hatte sich sein Patient der von ihm vorge- schlagenen Operation seiner Analfistel verweigert. Nun reckte er ihm den After ent- gegen, bereit, einige schmerzhafte Schnitte zu ertragen,
Backgrounder on Financial Risks of Proposed New Reactors in the United States (This backgrounder relied on analyses and media releases by Taxpayers for Common Sense, Friends of the Earth, and Southern Alliance for Clean Energy, referenced at the bottom) Two AP1000s proposed at Vogtle nuclear power plant, Georgia The first conditional U.S. federal nuclear loan guarantee was awarde