Chemie - 2.Test

Alexander Neuherz

NW2/CHEMIE – Teststoff, 1. Test
Chemistry

Carbon Chemistry
 Its organic chemistry
 Carbon is an heat residence matter
 Used in formula one and by professional cycles
 Very light
 Very flexible
 Carbon dioxide, carbon monoxide, carbon hydroxide
 Carbon binds only with carbon

Carbon has 4 valence electrons and the oxidation numbers are IV, -IV, 0 (elementary compound)

There are 3 elementary modifications:
1. Diamond
2. Graphite
3. Fullerenes

Differences between Diamond and Graphite:

Diamond
Graphite
Transparent
Gray, black
Brilliant
Opaque
Hardness on the Mohs scale: 10 (hardest possible)
Hardness on the Mohs scale: 0,6 (very soft)
Isolator, insulator
Electrical conductor
Each of the 4 valence elektrons are strongly bound
Three electrons are strongly bound, the fourth is
between the sheets weakly bound
Tetrahedron: (3-sided pyramide)
Hexagonal rings:




About Fullerenes:
The best known fullerene is the “bucky ball”. The “bucky ball” has been synthesized
by Wolfgang Krätschmer in 1990.

The compound has been named “bucky ball” after the American architect
Buckminster Fuller. It looks like a soccer ball and has 60 C-atoms. (C60)


Nanotubes belong to the fullerene family. Graphite layers are rolled up to tubes.
(Diameter: few nanometer, length up to 18 cm)
The strength of nanotubes is 5x higher than steel and nanotubes are nearly
lightness.

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Alexander Neuherz

NW2/CHEMIE – Teststoff, 1. Test

C02 - Carbon dioxide
Carbon dioxide is colorless (farblos), odorless (geruchlos) and tasteless (geschmacklos).

Use of C02:
 Food industry
 Carbonated water (carbonated soft drinks)
 Fire extinguisher contains liquid CO2 under pressure
 Toxicity: 8-10% Volume
Lewis-structure

CO2 turns in water litmus (Lackmus) from blue to pink.
We got the carbonic acid (=Kohlensäure).

Phase diagram of CO2


Unpolar covalent bounding




polar covalent bounding
Polar bounding: EN > 0 < 1,7
Ionic bounding: EN > 1,7

C0 – Carbon monoxide
It is a toxic, colorless and odorless gas. It is a product of incomplete combustion (insufficient oxygen
supply) -> ungenügend Sauerstoffzufuhr.
 Exposure at 100 ppm to CO is toxic for humans
ppm – parts per million
 It combines with hemoglatin and prevent oxygen binding (it bindes 200-300 times stronger
than 02

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Alexander Neuherz

NW2/CHEMIE – Teststoff, 1. Test
Dissociation of Carbonic acid:


⇔

Hardness of water
General:
Hard water contains bicarbonate (hydrogen carbonate), chlorides and sulphates of calcium and
magnesium.
Hard water produces very little lather (Schaum) with soap. Soft water produces easily lather with soap.

Total hardness:
The total hardness includes all Ca++ and Mg++ ions that are determined by a Titriplex solution. This
solution contains EDTA and complexes Ca++ and Mg++.

Disadvantage of hard water:
 Hard water affects cleaning ability; a large amount of soap is consumed.
 Hard water can cause scaling (Ablagerungen) inside the pipes that transport water.
 Pipes can be corroded if using hard water.

Types of hard water:
Temporary hard water:
 Contains bicarbonate (hydrogen carbonate):
Ca(HCO3)2 and Mg(HCO3)2
 Both bicarbonates are water soluble.
 Bicarbonates can be removed after heating water to more than 60°C.
 Carbonathärte

Permanent hard water:
 Contains chlorides and sulfates of calcium and magnesium.
 These ions cannot be removed by heating the water.
 Nichtcarbonathärte

How comes lime into water?
Calcium carbonate (limestone, chalk) and magnesium carbonate are not water soluble.
CaCO3 is converted to calcium bicarbonate in presence of carbonic acid, which solubilizes to 0,1% in water
(a very small amount).
The same is true for magnesium Carbonate.

Reaction:
↔



If water is heated, limestone precipitates. (Kesselstein oder Kalkstein)

Definition of hardness
 1°d = 10 mg CaO in 1l of water
 1 Grad deutscher Härte entspricht 10 mg CaO in 1l Wasser
 1° d = 0,798° e = 0,560° f
 Wasserhärte:
o 0-7° d:
sehr weich
o 7-14° d:
weich
o 14-21° d: hart
o >21° d:
sehr hart
o >30° C:
als Trinkwasser nicht empfohlen

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