MSE 330 – Thermodynamics of Materials  Department of Materials Science and Engineering University of Michigan

     

Homework  #5  –  100  points    1 (25 points) Using the vapor pressure – temperature relationships for CaF2 (α), CaF2(β) and liquid CaF2, calculate: A – the temperatures and pressures of the triple points for the equilibria CaF2(α) - CaF2(β) – vapor CaF2 and liquid CaF2 - CaF2(β) – vapor CaF2 B – the normal boiling temperature of CaF2 C – the molar latent heat of the transformation CaF2(α) -> CaF2(β) D – the molar latent heat of melting of CaF2(β) You may find all relevant quantities in the Table document in Canvas.  2  (25  points)  The vapor pressures of zinc have been written as: (1) ln𝑝 𝑎𝑡𝑚 =  − !",!"#

!− 0.755𝑙𝑛𝑇 + 19.25

(2) ln𝑝 𝑎𝑡𝑚 =  − !",!"#!

− 1.255𝑙𝑛𝑇 + 21.79 Which of the two equations is for solid zinc? 3 (25 points) At the normal boiling temperature of iron, Tb=3330K, the rate of change of the vapor pressure of liquid iron with temperature is 3.72 x 10-3 atm/K. Calculate the molar latent heat of boiling of iron at 3330K. 4 (25 points) Using the phase diagram of Fe shown below, draw the free energy versus pressure curves at 1600, 800, 500 and 300oC.