課程名稱︰物理化學上
課程性質︰農化系必修
課程教師︰李弘文
開課學院：
開課系所︰農化系
考試日期（年月日）︰2012.12.03
考試時限（分鐘）：110分鐘
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
Part A: True/False questions(40 points, 2 point for each question)
For the statement to be true, it must be always true. If the statement is
false, simply circle the wrong statement or cerrect the statement to make it
true.
2 points for each correct answer, and 1 point will be subtracted from each
incorrect answer.
o
(a) For a spontaneous process at constant T and P, △G is always negative.
o
(b)△G is a temperature-independent constant.
(c) When urea spontaneously dissolves in water, the geaker of solution feels
cold. This is an entropy-driven process.
(d) Equilibrium constants (Kp) for reactions involving only gases depend on
trmperature, but not on pressure.
(e) △G is the maximum non-expansion work that a system can do at constant
T and V.
(f) In the case of 0.01 moles of Ar and 1 mole of N2 mixing together. at
constant T and P, the sign of △Smix, △Hmix, and △Gmix is (+,0,-).
(g) The negative change in Helmholtz free energy during an isothermal
process is the maximum work available from the processes.
(h) For real gas with compressibility factor Z>1, molecular interaction is
dominated by attraction potential.
(i) Both van der Waals parameters a and b are larger for Ar gas than those for
Ne gas.
(j) Nitrogen and methane gases in the corresponding states have the same
value of Z.
(k) Critical temperature (Tc) and creitical pressure (Pc) can be expressed by
van der Waals parameters a and b.
(l) For a one-component system, when the pressure is feduced, the amount of
the boiling temperature change is always smaller than that of the freezing
temperature.
(m) The Clausius-Clapeyron equation can be applied to a solid-liquid phase
transition.
(n) At equilibrium, a substance that occurs in two phases has the some
concentration in both phases.
(o)At constant temperature, for one-component system, μ(P2)<μ(P1) when
P2<P1.
(p) In the P-V phase diagram for a one-component system, the liquid/gas
coexistence is descrebed by a line.
(q) For an ideal solution of two substances A and B, μ must be smaller than
A
o
μ .
A
(r) When azobenzene of molar fraction of 0.05 is addid to a pure benzene
solution, the change of chemical potential of benzene is RTln(0.05).
(s) If solutions of a same single solute are prepared at equal molalities
but in different solvents, the boiling temperature change of the solvent
will be the same for these ideal solutions.
(t) Based on the phase rule, a two-component system with a liquid/gas
coexistence has no degree of freedom.
Part B: Calculation and Descreption questions:
(28pts)(1) At 298K, the vapor pressure of pure benzene is 96.4 torr, and that
of the solvent will be the same for these ideal soltions sontains 3.0 mole
of benzene and 2.0 mole of toluene. Assuming the ideal behavior, andwer
the following questions.
(4pts)(1A) Plot the P-Z phase diagram at 298K, and specify (a) the
benzene
bubble line (──) and dew line(----); (b) the phase at diffefent regions.
↑ ↑
│ │
P │ │
│ │
│ │
│ │
└───────┘
Z
benzene
(3pts)(1B) At 298K, when the pressure is reduced from 760 torr, at what
pressure would the vapor phase appear first?
(12pts)(1C)When the 1.5 mol of the solution has been converted to vapor,
calculate the molar fractions of benzene at liquid and vapor phase.
(5pts)(1D) Now toughly sketch the T-Z phase diagram at constant
benzene
pressure. Specify (a) the bubble line (──)and dew line(----) ; (b) the phase
at different regions; (c) the relative magnitude and physical meaning of
temperatures at Z =0 and 1.
benzene
↑ ↑
│ │
T │ │
│ │
│ │
│ │
│ │
└──────┘
(5pts)(1E) explain how "fractional distillation" works using typical
fractional distillation words using typical fractional distillation column in
organic laboratory. In the case of benzene and toluene mixture, which compound
can be purified at the top of the column?
(8pts)(2) First, disign a set of experiments to determine all the
o o o
thermodynamics parameters(K, △G , △H , △S ) of a biochemical reaction.
Then, explain how to use the experimental results to determine all 4
o o o
parameters. Assume that △G , △H and △S are constant over the experiments.
(8pts)(3) Sketch a P-T phase diagram of pure water. Specify (a) the phase in
each region, (b) triple point and (c) critical point. Also explain the sign
and magnitude of slopes along co-existence lines.
(8pts)(4) Calculate Kp at 298K and 500K for the reaction
1
NO + ── O →NO assuming that △H is costant
(g) 2 2 (g) 2(g) rxn
over the interval 298-600K. Do you expect Kp to increase of decrease at
temperature is increased to 600K?
o 3 -1 o 3 -1
△H (NO ,g)=33.2x10 Jmol , △H (NO,g)=91.3x10 Jmol
f 2 f
o 3 -1 o 3 -1
△G (NO ,g)=51.3x10 Jmol , △G (NO,g)=87.6x10 Jmol
f 2 f
(10pts)(5) A 2.75 mole of Ar undergoes an isothermal reversible expansion
from an initial volume of 5.0L to a final volume of 95.0L at 320K. Calculate
the work done in the process using (5A) the ideal gas and (5B) van der Waals
equations of state (dw=-PdV)
6 -2 -5 3 -1
(van der Waals paremeters of Argon:a=0.1355m Pa mol , b=3.2x10 m mol )
(6pts)(6) Benzene(l) has a vapor tressure of 0.1369 bar at 298K and an
enthalpy of vaporization of 32.72kJmol^-1, restectively. Calculate the
vapor pressure of benzene(l) at 340K assuming that the enthalpy of
vaporization does not change with temperature.
(12pts)(7)A protein P (membrane receptor) involved on signaling pathway has
been found to follow the following obligatory sequential binding scheme to
proceed with the signaling cascade:
Po + L ←→ PL + M ←→ PLM
K1 K2
Protein Po has to bind to ligand L first in order to bind to ligand M.
The dissociation constants of these two binding processes are K1 and K2.
(6pts)(7A)Express Y , the fraction of protein that is bound only by ligand
PL
L (PL), in the Langmuir form in terms of K1, K2, L, and M.
(6pts)(7B) Plot Y vs. [L] . Also, identify the value and position of the
observed dissociation constant Kobs, the maximum Ymax value in the plot.
↑
│
│
Ymax│_ _ _ _ _ _______
│ │ ／
Y │ │ ／
PL │ │╱
│ ∕
│∕│
└──────────→[L]
Kobs
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