kamaltokamak
07-17-2008, 01:13 AM
Suppose you have a system consisting of one mole nof arsine, kept under a constant pressure of 0.1 bar. At this constant pressure, the temperature of the system is raised starting from room temperature. Use the thermodynamic data given below to solve the following questions:
• At what temperature does the first As gas (either As(g),As4(g) or mixture of both ) appears?
• What is the composition of the gas phase at this T?
• At what T does the solid As disappears?
• At what T is there as much As present as As(g) and as As4(g)?
Clarify all approximations you make.
Delta_f_H(kj.mol-1) Sm(jk-1 mol-1)
As (S) 0.0 35.1
As (g) +302.5 174.2
As4(g) +143.9 314.0
2)
Solid methane (CH4,Tfus=91 k) and solid tetrafluoromethane (CF4,Tfus=89 k) are immiscible. As liquids, they are only partially miscible. The upper critical temperature of the mixture is 94 k at a mole fraction xCF4=0.43 and the eutectic temperature is 84 k at amole fraction xCF4=0.88. at 86 k, the phase in equilibrium with the CF4 rich solution changes from solid CH4 to CH4 rich solution. At this temperature, the two solutions in equilibrium have mole fraction xCF4 =0.10 and xCF4 =0.80, respectively.
• Draw the CH4- CF4 phase diagram.
• Estimate the enthalpy and entropy of fusion of CF4.
• At what temperature does the first As gas (either As(g),As4(g) or mixture of both ) appears?
• What is the composition of the gas phase at this T?
• At what T does the solid As disappears?
• At what T is there as much As present as As(g) and as As4(g)?
Clarify all approximations you make.
Delta_f_H(kj.mol-1) Sm(jk-1 mol-1)
As (S) 0.0 35.1
As (g) +302.5 174.2
As4(g) +143.9 314.0
2)
Solid methane (CH4,Tfus=91 k) and solid tetrafluoromethane (CF4,Tfus=89 k) are immiscible. As liquids, they are only partially miscible. The upper critical temperature of the mixture is 94 k at a mole fraction xCF4=0.43 and the eutectic temperature is 84 k at amole fraction xCF4=0.88. at 86 k, the phase in equilibrium with the CF4 rich solution changes from solid CH4 to CH4 rich solution. At this temperature, the two solutions in equilibrium have mole fraction xCF4 =0.10 and xCF4 =0.80, respectively.
• Draw the CH4- CF4 phase diagram.
• Estimate the enthalpy and entropy of fusion of CF4.