First order transitions:variation of equilibrium S.J.T.U. pressure with temperature(5) Phase Transformation and Applications eq ap △H Clapeyron equation dTeg Te△V Consider the change of the melting point of tin resulting from a pressure change of 500 atm 0AT9= AH 7196 Te△V 505×4.39×10-7 △p9=500atm△Teg=+1.58K The melting temperature rises as the pressure rises because all the terms at the right of the equation are positive In the case of water,the opposite is true since the specific volume of water decreases upon melting SJTU Thermodynamics of Materials Spring20o6©X.J.Jin Lecture 7 equilibrium IPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 7 equilibrium I First order transitions: variation of equilibrium pressure with temperature (5) VT H dT dp eq eq eq Δ Δ = Consider the change of the melting point of tin resulting from a pressure change of 500 atm Clapeyron equation 7 1039.4505 7196 − ×× = Δ Δ = Δ Δ VT H T p eq eq eq p Tatm K eq eq =Δ 500 +=Δ 58.1 The melting temperature rises as the pressure rises because all the terms at the right of the equation are positive In the case of water, the opposite is true since the specific volume of water decreases upon melting