Mahmoud El-Marsafy, Peter Schwarz, Metodija Najdoski
MATERIALS AND TECHNIQUES
1.1. No-cost
materials 6
1.1.1. Disposable containers
6
1.1.2. Tray and dust bin
8
1.1.3. Ampoule burners 8
1.1.4. Candle burner 10
1.1.5. Piezo-fuse from a
cigarette lighter 12
1.2. Low-cost
and other materials 14
1.2.1. Syringes 14
1.2.2. Two pan scale 15
1.2.3. Digital pocket scale
15
1.2.4. Digital multimeter
16
1.2.5. Wellplate 6
17
1.3. Measurements
of volume and mass 18
1.3.1. Preparation of syringes
for measurements 18
1.3.2. From milliliter to
microliter of water 20
1.3.3. Water and syringe
to measure volume of solids 22
1.3.4. Preparing a two pan
scale for weighing 23
Part II: EXPERIMENTS 25
1. Water in air, soil
and food
1.1. Water in the air 25
1.2. Water in dry soil 27
1.3. Water content in different
fats 29
1.4. Water content of egg,
potato and red cabbage 31
1.5. Potatoes in water and
in salt water 35
2. Properties
of water 37
2.1. Not all transparent
colourless liquids are water 37
2.2. Electric conductivity
of water samples 38
2.3. Density of different
water samples 41
2.4. Density 2: Anomaly of
water during cooling 44
2.5. Density 3: Divers in
fresh water and sea water 46
2.6. Density 4: Cartesian
diver 48
2.7. Freezing point: Change
of temperature during cooling water 51
2.8. Melting point: Change
of temperature during heating of ice 53
2.9. Boiling points: Change
of temperature during more heating 55
2.10 Boiling under reduced
air pressure 58
2.11. Increase of pressure
and volume during boiling 60
2.12. Decrease of pressure
and volume during condensation 62
2.13. Balloon experiment:
Volume changes in a microwave oven 64
2.14. Water cycle: Evaporation,
condensation, precipitation 66
2.15. Surface tension 1:
Metal floating on water 67
2.16. Surface tension 2:
More effects of washing-up liquid 69
2.17. Visualization of the
dissolving process 71
2.18. Comparison of solubility:
Sugar, salts, citric acid 74
2.19. Making a supersaturated
solution of sodium acetate 76
2.20. Volume change due to
mixing water and ethanol 78
2.21. Model experiment on
volume change due to mixing 80
3. Air and
oxygen in water 83
3.1. Water dissolves only
little air 83
3.2. Winkler test for dissolved
oxygen 85
3.3. Air supply and oxygen
consumption (BOD5) in a sewage plant 89
4. Separation
of pure substances mixed with water 95
4.1. Separation of sodium
acetate from a supersaturated solution 95
4.2. Crystallization of sodium
chloride from salt solution 97
4.3. Separation by using
difference in densities 99
4.4. Carbon dioxide gas from
Cola 100
4.5. Spaghetti dance in sparkling
water
..
. 102
4.6. Heating Cola to dryness
104
4.7. Pure water by distillation
of Cola 106
4.8. Paper chromatography:
Separation of dyes from felt tip pens 109
5. Chemical
reactions of water 111
5.1. Analysis 111
5.1.1. Volumetric reaction
of calcium and water 111
5.1.2. Drop electrolysis:
Decomposition of Petunia extract
by electricity 113
5.1.3. Electrolysis in a
pipette 116
5.1.4. Electrolysis of water
in two ampoules 118
5.2. Water by dehydration of minerals
121
5.2.1. Decomposition of malachite
121
5.2.2. Decomposition of transparent
gypsum mineral 123
5.2.3. Water by decomposition
of a copper(II) sulfate pentahydrate 125
5.3. Synthesis 127
5.3.1. Reaction of water
with copper(II) sulfate 127
5.3.2. Water by combustion
of methylated spirit 129
5.3.3. Water synthesis from
oxyhydrogen gas in a eudiometer 131
5.3.4. Photosynthesis: Water
for the biomass of growing barley 133
6. Water as acid and as base
137
6.1. pH indicator from blue
Petunia petals 137
6.2. Reaction with conc.
sulfuric acid: Water as base 1 140
6.3. Fountain with hydrogen
chloride gas: Water as base 2 143
6.4. Fountain with ammonia
gas: Water as acid 146
7. Molecule models from beads
joined by glue, wire or welding 149
7.1. Beads as models for
atoms and molecules 149
7.2. Beads as models to visualize
12C as relative atomic mass unit............... 151
7.3. Welding the bead model
of a fat molecule....................................152