Chemistry Reference
In-Depth Information
To brew coffee:
Extraction
To remove a stain:
Solubility
To wash clothes:
Emulsify and disperse
To use ink eraser:
Redox reaction
To produce photos:
Redox reaction, complex reaction
To polish silver:
Redox reaction
To dissolve mineral tablets:
Acid-base reaction
To bake with backing powder:
Acid-base reaction
To get rid of lime:
Acid-base reaction
To work with mortar:
Acid-base reaction
To use oven spray:
Solubility, saponification
In chemistry lessons, the mutual connections between chemical knowledge,
technological advance, and individual living habits can also be presented and
discussed in the historically development: soaps, detergents and cosmetics, preser-
vation of food, fertilization and pest control, drugs and pharmaceuticals.
Taking the diagram of Pfeifer, H
ausler, and Lutz (see Fig.
8.1
) as a basis of
everyday life experiences, there are a multitude of experiments with everyday
chemicals in accordance with this diagram and related scientific facts to be
considered. Beginning with “hygiene” in the middle of the diagram and continuing
with “health” and other aspects, these relations are introduced with examples of
special experiments (see E8.1-E8.16).
The reactions of the substances are sketched with reaction equations. For those
equations, it shall be indicated whether it is a redox reaction (RR), an acid-base
reaction (ABR), or a complex reaction (CR). In this sense, it is helpful to first teach
those three basic concepts systematically before everyday chemicals and their
reactions are shown by experiments and explained with the ideas of the basic concepts.
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8.2.1 Hygiene: Example “Bathroom Chemicals”
Tab cleaner
“
NaOH type
” (E8.1): This cleaner contains solid sodium hydroxide and
decomposes organic material by highly concentrated alkaline solutions - thus
blockages in the washbowl or toilet can be eliminated. If aluminum is added to
the cleaner, there is a reaction with water to form hydrogen and produce a vortex
that increases the cleaning effect:
Þ
4
ð
OH
ð
Al
ð
s
Þþ
3H
2
O
ð
1
Þþ
aq
Þ!½
Al
ð
OH
aq
Þþ
3
=
2H
2
ð
g
Þ
RR
;
CR
Hydrogen gas is detectable, but first “nascent” H atoms also react with nitrate
ions of sodium nitrate, which are added for safety:
NO
3
ð
OH
ð
8
f
H
gþ
aq
Þ!
NH
3
ð
aq
Þþ
aq
Þþ
2H
2
O
ð
1
Þ
RR
