1. There are three commonly encountered polymorphs in the Al2SiO5 system: andalusite, kyanite, and sillimanite. Thermodynamic data are given below. Thermodvnamic properties at 900K and 1bar(1bar=0.1MPa) (a) Calculate fG0 of andalusite, kyanite and sillimanite as a function of pressure (0.1,10,100,200, 300,400,500,600,700,800 and 900MPa) at 900K.(15pts) (b) Use the table you calculated to determine the equilibrium phase at each pressure, and estimate the rough pressure for each of the two phase-transitions. (Use the phase diagram for the Al2SiO5 system in my slides to check your answers.) (15 pts) (c) Calculate the Clapeyron slope for andalusite to sillimanite phase transition. (5 pts) (d) Comment on the possible sources of error in your thermodynamic calculations. ( 5pts)