ANSWERS: 3
  • At one atmosphere of pressure, the melting point of diamond is 3550° C. However, you would have to do this in an inert atmosphere. Diamond, being made of carbon, will burn at a temperature of only 800° C. So, if you leave diamond jewelry in a burning house, don't count on being able to recover it from the ashes.
  • Here's a few cut and paste quotes from various sources: If you were able to melt a diamond (this would have to be done in a container free of oxygen or the diamond would burn), when it cooled it would not be a diamond anymore. Note that the diamond is made of the element carbon. To be a diamond the carbon atoms have to be in a special order or stacking relative to each other. When you melt the diamond the carbon atoms are no longer in this special order and when it cools back down they do not return to the original stacking. There are other forms of carbon, such as graphite and amorphous carbon. Most likely you would end up with amorphous carbon. ---- Wealthy chemist Humphry Davy in the early 19th Century put a diamond in an evacuated bell jar, then focused sunlight on it to heat it. The diamond changed to graphite before his eyes. Later, Davy and Michael Faraday burned a diamond and proved that the only product was carbon dioxide, showing that diamonds were pure carbon. --- The melting point of diamond at atmospheric pressure is the highest of all known materials, so its melting point must be measured under high pressure and the melting point at atmospheric pressure calculated from thermodynamics, which is quite reliable. At 1 atm the melting point is about 4000 K +/- ~200 depending upon whose measurements you believe. However, the melting temperature drops to about 1200 K at 600k-bar. Both of these conditions are attainable in the proper equipment. --- According to M.w. zemansky's "Temperatures Very Low and Very High," a hot flame can be boosted to 5000 K by sending a high-voltage and low-current discharge across it in a process called "electrical augmentation." So that's one way it could be done. Also, arcs can maintain temperatures of 4000K, and even achieve temperatures of as high as 50,000K for a short time. Basically, 3800K is no problem. --- Also, see: http://invsee.asu.edu/nmodules/Carbonmod/point.html
  • 1-11-2017 Well, it's complicated. It's mostly a matter of pressure. Here is the long explanation: https://en.wikipedia.org/wiki/Carbon#Characteristics

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