課程名稱︰物理化學一
課程性質︰化工必修
課程教師︰陳立仁
開課學院：工學院
開課系所︰化工系
考試日期（年月日）︰2007/01/15
考試時限（分鐘）：110 min
是否需發放獎勵金：Yes
（如未明確表示，則不予發放）
試題 :
Physical Chemistry (Quiz for Chapter 6)
Problem 1 (20%)
Determine the mass percentage of carbon tetrachloride CCl4
(P1*=114.5 Torr, M1=153.823 g/mol) in the vapor phase at equilibrium
in a 1:1 mole ideal solution with trichloromethane CHCl3
(P2*=199.1 Torr, M2=119.378 g/mol) at 25度C.
Problem 2 (20%)
The following cooling curves have been found for the system
antimony (Sb) - cadmium (Cd):
Cd,wt%: 0 20 37.5 47.5 50
First break in curve, 度C: 550 461 419
Eutectic halt, 度C: 630 410 410 410 410
Cd,wt%: 58 70 93 100
First break in curve, 度C: 400
Eutectic halt, 度C: 439 295 295 321
Construct a phase diagram, assuming that no breaks other than
these actually occur in any cooling curve. Label the diagram
completely and give the formula of any compound formed. How many
degrees of freedom are there for each area and at each eutectic
point?
Relative atomic weight: Sb=121.757 and Cd=112.411
Problem 3 (20%)
A fictitious ternary system composed of liquids A, B, and C was
constructed by adding the component B to various binary A + C
mixtures and noting the point at which complete miscibility occurred.
The following are the mole-percents of A and B at which complete
miscibility was observed. Construct the phase diagram on a triangular
graph paper.
Xa(%) 10 20 30 40 50 60 70 80 90
Xb(%) 20 27 30 28 26 12 17 12 7
Problem 4 (20%)
Use Raoult's law to estimate the vapor pressure of a mixture of propyl
bromide (in liquid phase, mole fraction 0.381) and propyl chloride at
23度C. The CRC handbook gives vapor pressures as
log (P/Torr) = - 0.05223a/(T/K) + b
Propyl bromide: a = 32430, b = 7.821
Propyl chloride: a = 28894, b = 7.593
Problem 5 (20%)
In 1855, Matthew Fontaine Maury wrote The Physical Geography of the
Sea and its Meteorology, a book that was an immediate popular success
and remained in print for 20 years. In it, Maury quotes sea water
temperatures from all over the world. The coldest is the arctic ice bath,
which is brine (salty sea water) in equilibrium with icebergs. Maury
gives 27.2度F (-2.67度C) as the freezing point for this brine. A partial
phase diagram for the NaCl/H2O system is shown below. Use it to answer the
following questions. Note that the composition variable is percent by
weight, not mole fraction.
Picture (I can't draw it...)
(a)Do arctic icebergs taste salty?
(b)What is the molality of NaCl in arctic sea water?
(c)Suppose in your wonderings among the arctic ice you encounter a puddle
of brine in an iceberg with salt crystals at the bottom of the puddle.
What can you say about the temperature and composition of the brine in
the puddle.
(d)The diagram shows that a solution 23.3% by weight NaCl has the lowest
freezing point (-21度C). How well does this agree with the predictions
of our freezing point depression expression? If there exists a discrepancy,
explain the reason why. The freezing point depression constant Kf for
water is 1.86 K kg/mol. Molecular weights of Na and Cl are 22.9898 and
35.453 g/mol, respecively.
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