Unformatted text preview: α , β and γ holds: G α m = G β m and Δ S m = S α m-S β m = r βα T where r βα is the transition heat of phase β to phase α and T is the transition temperature. The following holds: r βα = r αβ and r βα = r γα-r γβ . ±urther S m = ± ∂ G m ∂ T ² p so G has a twist in the transition point. In a two phase system Clapeyron’s equation is valid: dp dT = S α m-S β m V α m-V β m = r βα ( V α m-V β m ) T ±or an ideal gas one Fnds for the vapor line at some distance from the critical point: p = p e-r βα /RT There exist also phase transitions with r βα = 0 . ±or those there will occur only a discontinuity in the second derivates of G m . These second-order transitions appear at organization phenomena . A phase-change of the 3rd order, so with e.g. [ ∂ 3 G m / ∂ T 3 ] p non continuous arises e.g. when ferromagnetic iron changes to the paramagnetic state....
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- Spring '10
- Thermodynamics, Fundamental physics concepts, Thermodynamic system, phase transitions