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Problem Session 7 problems0 (1)

# Problem Session 7 problems0 (1) - at 20 o C the vapor...

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Problem Session 7 problems Chapt 9 Fall, 2009 1. What proportions of ethanol and water should be mixed in order to produce 100 cm 3 of a mixture containing 50 percent by mass of ethanol? (b) What change in volume is brought about by adding 1.00 cm 3 of ethanol to the mixture? 2. By measuring the equilibrium between liquid and vapor phases of an acetone (A) – ethanol(E) solution at 57.2 C at 1.00 atm it was found that x A = 0.400 and y A = 0.516. Calculate the activities and activity coefficients for both components in this solution on the Raoult’s law basis. The vapor pressure of pure components at this temperature are: p A * = 786 Torr and p E * = 551 Torr. (x A is the mole fraction in the liquid and y A the mole fraction in the vapor.) 3. The total vapor pressure of a 4 mole % solution of NH 3 in water is 50.00 mm Hg

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Unformatted text preview: at 20 o C; the vapor pressure of pure water is 17.00 mm Hg at this temperature. Apply Henrys and Raoults laws to calculate the two partial pressures and the total vapor pressur of a 5 mole % solution. 4. A solution of sucrose in water freezes at -0.200 o C. Calculate the vapor pressure of this solution at 25 o C (accurate to 0.001 mm Hg). The vapor pressure of pure water at 25 o C is 23.506 mm Hg and the molal freezing-point constant for water is 1.86 o C/m. 5. The osmotic pressure of solutions of polystyrene in toluene were measured at 25 C and the pressure was expressed in terms of the height of the solvent of density 1.004 g/cm 3 . c/(gL-1 )2.042 6.613 9.521 12.602 h/cm 0.592 1.910 2.750 3.600 Calculate the molar mass of the polymer. 6. 9.17...
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