Microscale Chemistry Experimentation (advanced level)
MICROCHEM 1: Some experiment from
1. Batteries / Galvanic Cells / Electrolysis:
.
.
.
.
.
.
.
.
.
..
2. Food
.
.
.
.
.
.
.
3. Bead models of atoms, molecules,
ions, radicals
.
.
.
.
.
.
.
4. Explosion, Implosion
.
.
Time is money. Time-saving experiments could be didactic money.
Today’s requirements in modern chemical demonstrations and chemical
exercises are very
manifold. The experiments have to be designed so that they
• are as safe as possible for the teacher, the pupils and students
• are time-saving (preparation, performing, clearing away)
• are non-polluting to the environment (reduction of waste)
• are cost-saving (material, chemicals)
• can be referred to the every day life (no chemistry of chemicals)
• can be used to illustrate chemical theory.
Big difficulties to fulfill the above points frequently result from
chemistry teaching involving gases. But nevertheless experiments with gases
are an essential part of chemical education in high schools, colleges and
universities. Even in well equipped laboratories the timesaving handling
of bottled gases is very often restricted to hydrogen, oxygen, carbon dioxide
and nitrogen. Some of these gases must be generated in traditional gas
generators especially hydrogen chloride, ammonia, chlorine, carbon monoxide,
sulphur dioxide or hydrogen sulphide. Strict laboratory safety rules and
regulations in order to protect the environment on the one hand and lack
of time and money on the other hand due to cancellation of wellknown and
useful gas experiments with traditional equipment, described even in modern
lab books without innovation over the decades.
Small is beautiful
One way out for student’s activities is the change to microscale. To
perform chemical demon- strations in classrooms and also in big lecture
rooms new video techniques and projection devices can help to visualize
small scale experiments on the lecturer table for a big audience. But additional
possibilities occur with time- and cost-saving small scale techniques if
the distance between the lecturer and the auditory can be reduced. A badly
arranged experiment in a fume hood too far away from the audience or behind
a safety shield can be less impressive than a small scale portable apparatus
which needs no fixing stands and allows the lecturer to perform the experiment
closer to the students....
Using the same low cost material for student’s activities and for demonstrations,
many proper- ties of gases and violent reactions of stoichiometric
mixtures can be shown safely.
After spending a short time getting accustomed to the equipment the
described technique offers time- and costsaving possibilities in performing
small scale reactions with gases safely without polluting the environment....
SOME EXAMPLES OF EXPERIMENTS WHICH ARE WELL
KNOWN, BUT NEWLY
DESIGNED, SMALL SCALE, AND TIME SAVING
(DONE WITHIN 3-5 MINUTES):
1.Generation of sodium chloride using the elements...
2. Photolytic reaction between hydrogen and chlorine...
3. Hands on reaction between ethyne and chlorine...
4. Reaction between ethyne and oxygen...
5. Reaction between hydrogen and oxygen...
6. Doebereiner’s Lighter...
7. Generation of sulphuric acid - a hands on experiment...
8. Small scale ammonia fountain...
9. Desulphurisation plant (Four reactions within five minutes)...
10. Low Cost Apparatus for water electrolysis...
Literature:
[1] Obendrauf, V., Experimente mit Gasen im Minimaßstab. ChiuZ.
1996, 30, (3) 118
[2] Obendrauf, V., Die Wasserzerlegung im Schülerversuch. Chem.Sch.
(Salzbg.) 1998,
Nr. 4, S. 13
[3] Obendrauf, V., Von flüchtigen Flüssigkeiten und satten
Dämpfen. CHEMKON 1999,
Nr. 3, S. 118
[4] Obendrauf, V., Die Low-Cost-Lachgas-Kanone. PdN-Ch. 48 1999, Nr.
3, S. 35"
[5] Obendrauf, V.,Low cost gas generation for small scale hands on
experiments. 16th ICCE, 2000 Book of Abstracts S. 8-15.
.......................
.
.