Modifikace chemického experimentu v racionalizaci experimentální přípravy budoucích učitelů chemie

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.