Pressure, kbar

400 600

Pressure, kbar

Fig. 5.5 The equilibrium phase diagram for carbon

Example: At what pressure does graphite transform to diamond at room temperature? Diamond has a higher density (and consequently a lower molar volume) than graphite, and Av^g = -2x10- m /mole. Assuming that this quantity is independent of pressure, which is equivalent to assuming that the compressibilities of the two allotropes are the same, the above equation can be integrated to obtain the pressure at which the free energies of the two forms are the same:

Agd-g = 0 = Agd-g(1 atm) + (pd-g - 105)Avd-g where pd-g is the transformation pressure (in Pa) at 300 K, which is the temperature at which

Agd-g(1 atm) = 2880 J/mole and Avd-g = above equation yields:

Agd (latm)

•2x10- m /mole are specified. Using these values in the

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Getting Started With Solar

Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

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