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If Graphite is heated to it's melting point, what happens?
It's a macromolecular structure, so the covalent bonds have to be broken to melt it right?(i think this is true, but please correct me if I'm mistaken). so then when it reaches its melting point (3900k) it would just break down into carbon liquid, because carbon is a liquid at this temperature. but yet on Wikipedia it states that graphite sublimes, but how is that possible when carbon isnt a gas until like 4300k?
i would be grateful if someone could explain this to me thanks !!!!!!
asked in science, chemisty



Messerwisser answers:

Carbon is a gas consisting of 100% carbon at 4300 K, but sublimation starts at lower temperature as long as it is diluted with other (inert) gases.
Compare wit gaseous water in air at different temperatures and pressures.


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agentju90 answers:

it um......sorry. um.......it.....melts?


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seacommander answers:

I think that the phase diagram for carbon in the link below shows that carbon can exist as a liquid only at high temperature and high pressure - above 100 bar, and that at pressures below this and at a temperature of around or in excess of 4000 degrees celsius the transition is from solid to vapour (sublimation),as mentioned in your Wiki reference. So, to recap, only at very high pressures (in excess of 100 x atmospheric pressure) and temperatures will carbon exist as a liquid.

http://dao.mit.edu/8.231/CarbonPhaseDia.htm


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