課程名稱︰普通化學乙
課程性質︰必帶
課程教師︰陳逸聰
開課學院：工學院
開課系所︰材料系
考試日期（年月日）︰96/11/20
考試時限（分鐘）：160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. In early experiments to characterize the atom, there are several simple
but very beautiful works. Please briefly describe the experiments in relation
to the determinations of the electron mass, the electron charge, and the
atomic model. (15%)
2.(a) Name the following compounds (5%)
Na3HPO4
Al2(SO3)3
SF2
SnO2
BaCrO4
(b) Write the formula for the following compounds(5%)
sodium peroxide
mercury(I) chloride
chromium(II) acetate
diphosphorus pentoxide
hydrobromic acid
3. Please give examples to acid-base reaction, oxidation-reduction reaction
and precipitation reaction.(6%)
4. The Maxwell-Boltzmann distribution is given as follows.
f(u)=4π*(m/2π*kB*T)^1.5*u^2*e^(-mu^2/2kB*T)
u= velocity in m/s
m= mass of a gas particle in kg
kB= Boltzmann's constant = 1.38066x10^(-23) J/K
T= temperature in K
(a)Draw qualitatively the plot of f(u) vs. u at temperatures T1>T2>T3.(3%)
(b)Could you get the equation for the most probable velocity Ump, from the
Maxwall-Boltzmann distribution law? (4%)
In an experiment to study the collisions in NH3(g) molecules, we prepare
the NH3(g) sample at 400K and 100mTorr.
(c) Could you estimate the number of NH3 molecules in 1cm^3 at this
experimental condition? (3%)
(d) If the radius of the collisional cross-section for NH3(g) molecules is
25 angstrom, could you calculate the mean free path for the NH3(g)
molecules in the sample? (3%)
(e) Using the Ump obtained in question (a), could you estimate the
collisional time period for the NH3(g) molecules in the sample? (3%)
5. (a)To describe the behavior of real gases, we need to make corrections to
the ideal gas law, PV=nRT. The usual equation to represent real gases
is van der Waals equations. Could you write down the van der Waals
equation and explain the physical meanings of the correction terms. (7%)
(b)From the following values of van der Waals constants, could you provide
some reasons as to why the constants vary in such a way? (8%)
a(atm L^2/mol^2) b(L/mol)
He 0.034 0.0237
Cl2 6.47 0.0562
CO2 3.59 0.0427
H2O 5.46 0.0305
6. Consider the decomposition equilibrum for dinitrogen pentoxide:
2N2O5(g) ───→ 4NO2(g) + O2(g)
At a certain temperature and a total pressure of 1.00 stm ,the N2O5 is
0.50% decomposed (by moles) ar equilibrium.
(a) If the volume is increased by a factor of 10.0, will the mole percent
of N2O5 decomposed at equilibrium be greater than, less than ,or equal
to 0.50%? Explain your answer.(4%)
(b) Calculate the mole percent of N2O5 that will be decomposed at
equilibrium, if the volume is increased by a factor of 10.0.(4%)
7. (a) From the followin table of molar heat capacities of various gases at
298K, could you give some explanations for the varying heat
capacities for different atoms/molecules?(5%)
(b) From the table, we see that Cp-Cv≒R=8.3148 J/K mol is kepr for all of
the listed atoms/molecules. What conclusion could you draw from this
regularity?(5%)
Gas Cv(J/K mol) Cp(J/K mol) Cp-Cv
He,Ne,Ar 12.47 20.80 8.33
H2 20.54 28.86 8.32
N2 20.71 29.03 8.32
N2O 30.38 38.70 8.32
CO2 28.95 37.27 8.32
C2H6 44.60 52.92 8.32
8. Consider a gas at an initial pressure of 5.0 atm and an initial of 1.0L
that undergoes a change to 1.0atm and 5.0L by two different pathways as
shown below.
P│
5├．A
│｜＼
│ ＼ ↘1
│ 2↘ ＼ 2 為光滑曲線
1├ —．
└┴───┴─V
1 5
Pathway one:a short-cut from Ato B in P-V diagram
Pathway two:a pathway along the isothermal curve.
Please calculate work(w), heat(q), internal energy(E) and enthalpy(H)
changes associated with the two pathways.(1 L atm = 101.3 J)(16%)
9. The combustion of 0.1584g of benzoic acid increases the temperature of a
bomb calorumeter by 2.54 °C.
(a) Clalculate the heat capacity of the calorimeter.(The energy released
by combustion of benzoic acid is 26.42 kJ/g.)(3%)
A 0.2130-g sample of vanillin(C8H8O3) is then burned in the same
calorimeter. The temperature increases by 3.25 °C.
(b) What is the energy of combustion per gram of vanillin and per mole of
vanillin?(3%)
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※ 編輯: billren 來自: 61.228.89.88 (11/21 17:26)