Uranium Tetrafluoride & Osmotic Pressure Questions

Chem 3433-63342, Physical Chemistry 1

When possible, use the values for constants from our text. If you get them from other sources (if they are not in the book) cite where you got them from.


  1. (10 pts) Phase diagram

Uranium tetrafluoride (Tm = 1035 °C) and zirconium tetrafluoride (Tm = 912 °C) form a continuous phase of a solid solution with a minimum melting temperature of 765 °C at X(ZrF4) = 0.77. At 900 °C, the liquid solution with X(ZrF4) = 0.28 is in equilibrium with a solid solution with X(ZrF4) = 0.14. Also, the solution with X(ZrF4) = 0.87 is in equilibrium with X(ZrF4) = 0.90.

Based on this information, sketch the phase diagram. Explain what happens if a solution at X(ZrF4) = 0.10 and 1050 °C was cooled slowly to 800 °C. At 975 °C and X(ZrF4) = 0.10, how many phases are there , what are their compositions and what are the their relative amounts?


  1. (10 pts) Boiling point or FP problem.

M&S, P25.41 (please try not to look at the answer in the book.)


  1. (10 pts) Osmotic pressure estimate for polymer.

The osmotic pressure of polymer solutions were measured at 30 °C to be:

c (mg/mL) 1.33 2.10 4.52 7.18 9.87

π (N/m-2) 30 51 132 246 390

The densities of the polymer and solvent (toluene) were: 1.25 and 0.858 g/cm3, respectively. Estimate the molecular mass of the polymer and the second virial coefficient. Remember the plot can be a straight line or curved and may take either a linear or 2nd order fit.


  1. (10 pts) Activity coefficient

Calculate the activity coefficient, g+/- for aqueous KCl for A) 0.02 m KCl and B) a mixture of 0.02 m KCl in solution with 0.02 m Na2CO3. m = moles/kg solvent. Why are they different or the same?



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