課程名稱︰物理化學一
課程性質︰必修
課程教師︰戴子安
開課學院：工學院
開課系所︰化工系
考試日期（年月日）︰101.01.09
考試時限（分鐘）：150分鐘
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
1.(40 points)
Explain the following terms or physical phenomena. Use graphs if necessry.
(a) Plot the Gibbs energy vs. the extent of reaction, ξ, for a reaction that
goes nearly to completion and indicate its corresponding reaction Gibbs
energy on the plot.
(b) For a simple gas reaction A → B, plot the Gibbs energy vs. the extent
of reaction for the corresponding hypothetical without any mixing and
without any reaction.
(c) Consider an endothermic reaction A → B and the density levels in B are
much greater than those in A. Explain at the equilibrium why B molecules
can be dominant based on the Boltzmann's theorem.
(d) Explain how pressure affects equilibrium composition for a reaction.
(e) Explain how pressure affects the melting and boiling points for a pure
spcies.
(f) Based in the Ehrenfest classification, plot μ, V, H, S, Cp as a function
of temperature for the first order transtion.
(g) Explain how the activity of a liquid in a mixture can be determined.
(h) Plot phase diagram in the terms of T. vs. composition for a binary solution
that shows a positive deviation from the Raoult's law.
(i) For a nicotine/water mixture, explain why the system shows both LCST and
UCST.
(j) Calculate the pressure differential of water across the surface of a
spherical droplet of radius 100nm at 25°C(The surface tension for water is
γ=71.97 mN/m .)
2.(10 points)
At 2000°C, water is 2％ dissociated into oxygen and hydrogen at a total
pressure of 1bar.
(a) Calculate the equilibrium canstant Κ for H2O(g) = H2(g) + 1/2 O2(g)
(b) Will the extent of reaction increase or decrease if the pressure is reduced
(c) Will the extent of reaction increase or decrease if argon gas is added,
holding the total pressure equal to 1bar?
(d) Will the extent of reaction change if the pressure is raised by addition of
argon gas at constant volume to the closed system containing partially
dissociated water vapor?
3.(15 points)
The shells of marine organisms contain calcium carbonate CaCO3, largely in a
crystalline form known as calcite. There is a second crystalline form of a
calcium carbonate known as aragonite. Physical and thermodynamic properties of
calcite and aragonite are given below.
───────────────────────────────────────
Properties(Τ＝298Κ,Ρ=1bar) calcite aragonite
───────────────────────────────────────
Δf Η° (kJ/mol) 1206.9 1207.0
───────────────────────────────────────
Δf Ｇ° (kJ/mol) -1128.8 -1127.7
───────────────────────────────────────
Ｓ° (J/Kmol) 92.9 88.7
───────────────────────────────────────
Cp° (J/Kmol) 81.9 81.3
───────────────────────────────────────
Density (g/mL) 2.71 2.93
───────────────────────────────────────
(a) Based on the data given, would you expect an isolated sample if calcite at
Ｔ=298Ｋ and Ρ=1bar to convert to aragonite, given sufficient time?Explain
(b) what pressure must be achieved to induced the conversion of calcite to
aragonite at Ｔ=298Ｋ. Assume both calcite and aragonite are incompressible
at Ｔ=298Ｋ .
4.(10 points)
Calculate the Δr Η° and Δr Ｓ°for the reaction N2(g) ＋ O2(g)＝2NO(g)
from the folling values of equilibrium constant Κ.
┌────┬───┬───┬───┬───┬───┬───┬───┬───┐
│Τ∕Κ │ 1900 │ 2000 │ 2100 │ 2200 │ 2300 │ 2400 │ 2500 │ 2600 │
├────┼───┼───┼───┼───┼───┼───┼───┼───┤
│Κ/10^-4│ 2.31 │ 4.08 │ 6.86 │ 11.0 │ 16.9 │ 25.1 │ 36 │ 50.3 │
└────┴───┴───┴───┴───┴───┴───┴───┴───┘
5.(10 points)
Show that if the vapor pressure of a solute follows Henry's law, then in dilute
solution its chemical potential follows an equation very much like that for an
ideal solution.
6.(10 points)
A solution of polystyrene in benzene contains 10g/L. The equilibrium height of
the column of a solution (density =0.88g/cm3 ) in the osmometer corrected for
capillary rise is 11.6cm at 25°C. What is the molecular weight of the
polystryene.
7.(15 points)
The temperature-composition diagram for Ca/Si binary system is shown below.
(a) Identify eutectics, congruent melting compounds, and incongruent melting
compounds,
(b) If a 20 percent by atom composition melt of silicon at 1500°C is cooled
to 1000°C, what phases(and phase composition) would be at equilibrium?
Estimate the relative amounts of each phase.
(c) Describe the equilibrium phases observed when an 80 percent by atom
composition Si melt is cooled to 1030°C. What phases, and relative amounts
would be at equilibrium at a temperature
(i) slightly higher than 1030°C
(ii) slightly lower than 1030°C
(d) Sketch the cooling curve if the 80 percent of Si melt is cooled to the room
temperature.
第七題附圖 http://ppt.cc/Mm-B
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