Melting iron

[HydrogenBond]

The melting point of iron is 1811K and the boiling point is 3134K. http://en.wikipedia.org/wiki/Iron.

 

These are temperatures one may find in the mantle of the earth, thereby assuring that iron will be part of the fluid mantle solution. The center of the earth is suppose to be 10-15 thousand degrees K and is suppose to be metallic iron, how does iron vapor dissolved within a mantle solution rich in oxygen phase separate into a pure solid at a temperature roughly 10,000 degree higher?

[Tarantism]

how does iron vapor dissolved within a mantle solution rich in oxygen phase separate into a pure solid at a temperature roughly 10,000 degree higher?

 

i looked around for the answer to that question, and i found one website.

 

http://www.key-to-steel.com/Articles/Art86.htm

 

i dont know if th info that you are looking for is there however.

 

hope that helps!

[HydrogenBond]

Thanks for the research. I was actually questioning the theory of the earth's iron core. It make little sense that iron could phase separate out of a dissolved state within the mantle oxygen, yet this theory is accepted as scientific fact. Maybe there is an explanation or experimental proof that supports the theory that I am not aware of.

[Tarantism]

well, have patience with me on this one, but my understanding of your statement is that the iron in the earth's core remains a solid even at temperatures of 10k degrees! i looked for the answers for that one, but there were none that google could think of. if you find the answers however, please let me know. maybe this topic is best moved to the earth science forum?

[GAHD]

t's nickel and Iron mostly, with a fair degree of other heavy elements.

 

The logic is simple: heavy falls to the center of the gravity well, the lighter floats to the top. at the center of the well, the pressure from the other matter stops the iron from being a liquid by effectively raising it's boiling point.

 

The same thing happens when water on the ocean foor comes in contact with magma; it can reach several hundreds of degrees, but can't flash-boil because of the water around it. hope that helps a bit

[HydrogenBond]

That may work if metals like iron stayed as separated liquids or solids during the journey to the center of the earth. The odds are that the iron would become part of the mantle as it melted/dissolved during its long journey. An iron core would require some potential to phase separate from dissolved iron back into a single phase. This could be done with a strong reduction potential like hydrogen or carbon within the early mantle. But the emormous residue of hydrogen and carbon, i..e, water, CO2, etc., are not observed seeing the core is 1000 times larger than the oceans. The water at the bottom of the oceans is not much different in compostion than the water at the top. Gravity is not able to overcome the chemical potentials. The gravitational potential is lower in the center of gravity due to vector addition. The pressure and temperature are higher compounding the problem for the iron.

[Vending]

As to why is the iron core liquid/solid?

 

The answer is that there is enormous pressures in the center of the earth that favor those states.

 

 

As to the question why is the iron pure?

 

Well, imagine this. At the time of its formation, the earth was all pretty much hot and molten. When the earth started to cool, the first part to become cold enought to be solid must have been the outer surface of the sphere. Thus, the crust of the earth was formed. Now, this crust protected the inner part of the earth from the intrusion of further oxygen. Thus, any formation of iron oxides (or other iron complexes) could only use the oxygen that was present in the inner earth at the time of the formation of the crust. Assuming that there was not enough oxegen in the inner earth to react with ALL of the iron (i think this is a pretty good assumption given that most of the oxygen apparently was captured by silicon) then after all the oxygen had been used up, there must have been elemental iron left over. It is this left over iron that forms the core of the earth.

 

That is why there is pure iron in the earth. (i think)

[Boerseun]

The fascinating thing is that we can conjecture about the constitution of the Earth's insides - for ever.

 

And the only way we'll ever know what's actually inside, would be to actually blow the sucker up and see. Thereby pissing off Greenpeace to the n'th degree! And wiping out humanity at the same time!

 

Imagine - a bunch of scientists in the year 4235 AD still wondering what shakin' at the Earth's core... Talk about final frontiers!

[GAHD]

HydrogenBond, you havn't played with a smelter much, have you? The pressure and temperature being high do not compund a problem, they actually make it more likely: Chemical bonds deteriorate at high temperature, that is the basic function of a reduction furnace. In a furnace oxygen burns with carbon to prduce carbon oxides and provide heat; the carbon oxide gets forced past and through the moltem Iron, which has it's bonds with other 'impurities' weakened by the heat.

 

Regardless of the compounds that could(and likely do) occur within the earth, the heat and pressure provided by gravitational 'kneeding' from the moon and the earth itself provides much more heat than is required to break most bonds and reduce iron and nickel to relatively pure states once you start moving deeper.

 

draw a sphere, divide it in half, then the halvs into quarters, quarters to eighths, and finally sixteenths. label the points 1-16. You will note that 1 & 9 form one of the lines running straight through the center, along with 2&10. So far, this is great to show a sigularity effect at the center, but what most don't realise is that this is far too simplistic.

 

all the points drawn thus far need to be connected to each other, not just to the center, so a line needs to be drawn from 2 to 9, from 3 to 8, from 1 to 10, etc... once you finish connectin all those lines, you will quicly see a 'web' forming. points with more intersections have more force exerted on them.

Now comes the fun part: overlay this picture onto sliced open picture of Earth.... :)

The pressure on the core is greater than anywhere else, regardless of vectors because it has to push back on everything else in the sphere. Gravity from all sides of the sphere is pulling not only at the center, but on every other point in the sphere too, resulting in a rather potent nexus of force at and near the center. As said ealyer, it's at this point that the pressure would force the boiling points to increase, thus forcing Iron & nickel back into crystaline structres.

 

If you think Iron would be trapped by much in the mantle, you really need to learn how molten iron works: It will literally burn and push through nigh-odd anything in it's path untill it cools, and once you go down a few hundred klicks, it's not cooling, it just starts taking on heat.

 

The amounts of certain elements does not mean that there is an equal amount of reactive elements: if the earth doesn't have enough oxygin to rust all the iron it contains, that's just too bad for entropy.

 

Quite simply put, heavy things sink, and light things float. Fe and Ni are just some of the most plentiful 'heavy' things we have around us. The quantities of each of these elements to which we have access is a testament to how much did manage to get trapped up and out before falling 'down'.

[DFINITLYDISTRUBD]

And the only way we'll ever know what's actually inside, would be to actually blow the sucker up and see. Thereby pissing off Greenpeace to the n'th degree<<<<<<<hahahahahahahahahahahahahahahah!!!!!!!!!!!!!!!!!!!!!!!!!!!!

^This is trully one of the most hilariuos responces I've ever seen here!!!!

 

But seriously I firmly believe that if you compress any liquid or gas far enough you get a liquid that is so dense that it "appears to be a solid" simply because the molecules have no way to get out of the way of each other give them room to move they probably will in a nice viscous manner.

 

Now a question of my own why does steel require nearly 1000 deg. more than the base iron it's made from to melt?

[HydrogenBond]

If one compresses any chemical material enough, the outer orbitals that define its chemical properties will begin to overlap in space, i.e, the space for the electron clouds of atoms have decreased due to the pressure and temperature. This will be a repulsive situation, that will require the overlapped chemical orbitals rearrange themsevles to form orbital combined arrangments of lower potential. What this new state of matter may be, is conjecture, but one would expect whole new properties from the materials, which should no longer obey the laws the surface chemistry (surface chemistry uses stable chemical orbitals) but rather whole new material properties associated with the orbital overlap/modification. The iron core assumes the extrapolation of surface chemistry, which may not apply in the core of the earth.

 

Relative to iron, the mantle is full of oxygen. Silica type materials can not exist at the high temperatures and pressures of the mantle. In the mantle all the surface chemistry breaks down. The oxygen is therefore free of any surface chemical bonding. Iron slag flowing through the mantle will more than likely also lose the metallic chemical bonding properties that keeps it a uniform phase. It will become a dissolved part of the mantle taffy. With orbital overlap increasingly occuring as we reach the core, (maybe why it becomes solid), for iron to now phase separate would need a potential.

 

The iron core assumption is based on two things. Iron is assumed to be the terminal atom of exothermic fusion. Secondly, iron has magnetic properties. This is a logical explanation of the core, but it still create a phase separation problem, unless the iron core of the earth somehow formed first (magnetic plus gravity attraction?) and the rest of the matter formed around this core via gravity. Any additonal iron from meteors would become part of the mantle taffy, some of which will return to the surface through magma convection.

 

The observation of craters on the moon led to the asteroid theory of the earth's iron core. But another way to look at the craters of the moon is early moon mantle convection and volcanos. This would better explain the larger craters and why the moon did not crack/shatter under the needed magnitude of the impacts. Or maybe, it was combined affect, where a few big impacts, weaken the crust and stir up the mantle taffy leading to a period of active volcanic modification.

 

I am not married to any one theory, although I am still intuitively partial to a fusion core in the center of the earth, because it can accommodate the widest range of phenomena, such as why the core spins faster than the rest of the earth. The mantle taffy is probably more like glue (taffy) than grease (gaseous), requiring a constant extreme energy output source for the core to spin faster than the rest of the earth.

[DFINITLYDISTRUBD]

Stupid question: how the f do they know that the earth"s core spins faster?

Is this theory hypothesis or fact?

[HydrogenBond]

It was a Nasa study. They used very long wavelength radiation. This makes the earth look translusent. From this they can see the layers. Using the Space Shuttle over one of the poles, were also able to show the movement of the core's interface layer, relative to the surface and it was going faster, by about one turn every 500 years. Not much, but to me it seems to indicate an engine of sorts in the center of the earth. That is the simplest way to explain how it could overcome so much visco-elastic friction, even after five billions years. The magnetic field is the exhaust emission from the engine.