Monday, April 16, 2012

How to make iron (5) - Carbon on planet Earth

In the previous post I asked how we get the normal carbon for the described carbon cycle to work.

We get the answer in nutshell from professor Kaler:

Begin with stars more or less like the Sun, those with masses from about 0.8 times that of the Sun to about 10 times the solar mass. When the fuel in a solar-type star's core runs out, the helium core contracts under the effect of gravity and heats up.

Hydrogen fusion then expands into a shell around the old burnt-out core, and so much energy is produced that the star temporarily brightens and expands by many times over, the expansion cooling the surface, turning the star into a class M "red giant."

When the temperature hits around 100 million degrees Kelvin, the helium is hot enough to fuse into carbon (through the near-simultanous collision of three helium atoms) and even a bit further, into oxygen.

This new power source stops the core's contraction and the star stabilizes for a time, dimming and heating somewhat at the surface. We commonly see these helium-fusing stars as yellow-orange type K giants.

Thank you Sir, that is very clear and understandable description of the nuclear reaction, fusion of helium into carbon and also into oxygen!

Mineral Information Institute tells us about carbon and my respect for the black stuff grows exponentially when reading this:

Named from the Latin word meaning "charcoal", carbon is an extremely important element. Carbon has a phenomenal and unique ability to create an astonishing number of different compounds--over 10 million different compounds of carbon are known. Carbon is the only element which has an entire branch of chemistry devoted solely to it and its reactions--organic chemistry-- so named because most of the compounds that all life requires contain carbon. Natural carbon occurs in several different forms, including graphite, diamond and the rare buckminsterfullerene (C60). Graphite carbon is used in steel making, printing, sugar refining, respirators, water purification and treatment and in pencil lead and batteries. Diamond carbon is used in jewelry and in many cutting applications. Diamonds also have the distinction of having the highest melting point of any substance (35700C). Buckminsterfullerene is currently too rare to have any industrial use but it holds great potential for the future. The many carbon compounds make up one of the largest and most useful group of substances that exist.

Biologic Rating: Essential for life processes in plants and animals.

Biological Benefits: Carbon is a critical element to all life. It is one of the six bulk elements and is the second most common element in the human body. It is a constituent of DNA, the primary building block of all organic matter. Life is intimately involved in the carbon cycle. Carbon dioxide is converted through various life processes into many different carbon compounds, which are then converted to fossil fuels by decay processes, which, when burned, reforms carbon dioxide. Some carbon compounds such as CO or CN- are very dangerous.

Percentage Amount in the Human Body: 22.85 %
MII page on Periodic Table

And this stuff is made in the Star factories up there in the heaven!

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