What is the boiling point of coal


 
Carbon occurs in several modifications. The extremely tough one diamond and the very soft one graphitediffer in many characteristics and yet they contain the same basic substance. The Fullerenes also occur naturally, for example in meteorites or in shungite, a black, coal-like rock. The Londsdaleit is a soft diamond with a Mohs hardness of 3, which crystallizes in the hexagonal crystal system and has a meteoric origin. Lit [63]

The diamond crystallizes in the cubic crystal system. It is the hardest of all known and natural substances, it has the best thermal conductivity - it is up to five times better than silver - and the highest melting temperature of all substances. When heated in the absence of air, it changes to the very soft and black graphite at around 1500 ° C. A diamond can only be burned in a stream of oxygen; when heated with a welding torch, the diamond turns dark on the surface without burning, which indicates the formation of graphite. The author failed to actually burn it in this way.


Floating graphite plate
 

 
The graphite is diamagnetic and is repelled by the neodymium super magnets.


There is carbon that has weak ferromagnetic properties. The carbon modifications graphite and diamond are diamagnetic. They are easily repelled by a super magnet. The graphite is more diamagnetic than the diamond. Diamagnetism explains the phenomenon why you can let a graphite plate float over several neodymium super magnets.

Carbon occurs in other forms during technical processing: These include soot, activated carbon, amorphous carbon, carbon fibers, glassy carbon, carbon nanotubes, carbon nanofoam or amorphous carbon.Lit [35] Graphene, a two-dimensional, honeycomb-like carbon structure, is also of technical importance each carbon atom is linked to three other carbon atoms. Coal types such as hard coal, anthracite or brown coal were formed over the millennia through transformation from former living beings.
  
When graphite evaporates, so-called carbon clusters are formed, which are also known as fullerenes. These are the only carbon modifications that are soluble in organic solvents such as toluene and form colored solutions. Otherwise they also show a rather strange behavior when reacting with other substances. Like diamonds, fullerenes do not conduct electricity. The best known is Buckminster fullerene, which consists of 60 carbon atoms and was named after the American engineer and architect Richard Buckminster Fuller (1895–1983), the inventor of cantilever dome structures. Lit [4]


Structure of a C60-Buckminsterfullerens
 
 


 
The carbon atoms form 15 pentagonal and 20 hexagonal rings and are on the surface
an (imaginary) sphere with a diameter of just under a nanometer.


The carbon modifications are stable at room temperature; at higher temperatures they burn to form carbon dioxide CO2If the combustion is incomplete, the poisonous carbon monoxide CO is formed. Ethyne can be produced from carbon and hydrogen in an electric arc:

2 C + H2  C.2H2

When heat is supplied, glowing carbon reacts with water vapor to form carbon monoxide and hydrogen. This mixture is also known as water gas:
  
C + H2O CO + H2       ΔHR. = +131 kJ / mol
  
In red heat, carbon reacts with sulfur to form carbon disulfide CS2, with nitrogen in an electric arc to dicyan C2N2 and with silicon at 2000 ° C to silicon carbide SiC. The element carbon has the ability to form long chains and ring structures in chemical compounds, also in hydrocarbons. For this reason, most organic compounds are made up of carbon atoms in their basic structure; they are considered to be the hallmarks of life on earth.
  
 
Soot formation and charring
 

 
Carbon-containing compounds soot or char when heated.
   

When carbon-containing compounds are burned, soot and charring are obtained, depending on the carbon content. When wood is heated, charcoal is produced. If the combustion of a candle flame is disturbed, for example by holding a porcelain bowl in the flame, only incomplete combustion takes place. The resulting soot could be burned further with oxygen to form carbon dioxide.