Scientists Melt Diamond

here's my question: since I am an engineer, these questions raise up automatically to me:
1. How do you make water boil at under 100'C? Easy, Put water in a vacuum
2. The reverse, how do you make water boil at a higher temperature? Easy put it under pressure
-Once water is under a concealed space under pressure, the water molecules will need more heat energy to turn into steam.
3. So my third question is, why would putting a diamond under extreme amounts of pressure help melt it?
4. Yes they make diamond in laps, they are called industrial diamond usually used in the engineering world as cutting diamond. Now, to make these diamond, we put Carbon under extreme pressure and then apply heat to create diamond
-Once again, how would putting diamond under extreme pressure help it melt?

FruitPunch,

They reached it's triple point, which requires a combination of both pressure and temperature. Water can't be used as an example of the typical phase diagram because it's bizarro substance. It doesn't act like other things.

Check this page out (I know it's wikipedia, but it's right). Note the graph on the right.

en.wikipedia.org...

and look at this phase diagram



See how water does that goofy turn back shown with the dashed green line? Well, other substances follow the solid green line. So, taking carbon, you would have to increase both temperature and pressure to get to its triple point (its melting point).

Just for clarification, you have to increase both temperature and pressure to get to water's triple point as well, but to take the behavior of water after it's triple would make you think wrongly about other materials.



[edit on 11-11-2006 by Valhall]