article Rationalization for the modification of chemical experiments for future
chemistry teachers
Václav Richtr, Lukáš Novák
information
year: 2019
issue: 1
fulltext: PDF
online publishing date: 28/2/2019
DOI: 10.14712/25337556.2019.1.2
ISSN (Online): 2533-7556
Toto dílo podléhá licenci Creative Commons Uveďte původ 4.0 Mezinárodní License.
abstract
This paper focuses on the possible modifications of time-consuming and materially demanding experiments for teaching purposes. The aim is the complex utilization of experiments for demonstrative purposes, putting to an effect several principles and techniques, while best limiting the undesirable side effects observed in the original experiments. In the opening part of this paper the fundamental concepts are introduced. The significance of improvisations and modifications is illustrated with an example of the modification of burners which were originally designed for coal gas. The principle of these modifications lies in constriction of the gas nozzle for the purpose of using natural gas instead. As an example of the rationalized modification, suitable for sundry levels of education, is introduced the ethyne preparation as the hydrolysis of calcium carbide in the specially designed simple apparatus. Suggested modification enables to monitor basic properties of emerging ethyne, while securing conditions out of danger. A modification of the platinum catalyzed oxidation of alcohols is the second example. The mentioned embodiment enables monitoring of an oscillatory reaction. The modification is originally suggested for methanol oxidation, but it can be used also for ethanol oxidation when conditions are changed a little. The oscillatory reaction is divided into three phases: 1) reaction initiation by putting preheated platinum spiral into a flask above the alcohol surface, 2) supplanting some air oxygen by an emerging aldehyde and slowing the processing reaction, 3) fresh air influx into the cooling flask to start reaction again.
keywords
modification, improvisation, rationalization, real experiment
fulltext (PDF )
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