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F12_EMS_160_HW7

# F12_EMS_160_HW7 - unmixed solid Au and solid Si At 636 K G...

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HW 7. Due: 11/18/11 NO CREDIT WILL BE GIVEN IF WORK IS NOT SHOWN!! Problems from textbook 9.4 Calculate the heat required to form a liquid solution at 1356 K starting with 1 mole of Cu and 1 mole of Ag at 298 K. At 1356 K the molar heat of mixing of liquid Cu and liquid Ag is given by Δ H M = -20,590 X Cu X Ag . 10.1 CaF 2 and MgF 2 are mutually insoluble in the solid state and form a simple binary eutectic system. Calculate the composition and temperature of the eutectic melt assuming that the liquid solutions are Raoultian. The actual eutectic occurs at X CaF2 = 0.45 and T = 1243 K 10.2 Gold and silicon are mutually insoluble in the solid state and form a eutectic system with a eutectic temperature of 636 K and a eutectic composition of X Si = 0.186. Calculate the Gibbs free energy of the eutectic melt relative to (a) unmixed liquid Au and liquid Si, and (b)
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Unformatted text preview: unmixed solid Au and solid Si. At 636 K G m,Au = 12,600[(1338-636)/1338] = 6,611 J G m,Si = 50,200[(1658-636)/1658] = 30,943 J a. G M = ab = -(0.186 * 30,943 + 0.814 * 6,611) J = -11,140 J b. G M = 0 10.3 Al 2 O 3 , which melts at 2324 K, and Cr 2 O 3 , which melts at 2538K form complete ranges of solid and liquid solutions. Assuming that S m,Cr2O3 = S m,Al2O3 , and that the solid and liquid solutions in the system Al 2 O 3 Cr 2 O 3 behaves ideally, calculate a. The temperature at which equilibrium melting begins when an alloy of X Al2O3 = 0.5 is heated b. The composition of the melt which first forms c. The temperature at which equilibrium melting is complete d. The composition of last-formed solid...
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