課程名稱︰物理化學上
課程性質︰必修
課程教師︰蘇志明
開課學院：生農學院
開課系所︰農業化學系
考試日期（年月日）︰2009 10 22
考試時限（分鐘）：130
是否需發放獎勵金：是
試題 :
1.Consider an aqueous solution of alanine amino acid(CH(CH3)(NH3+)(COO-)).
The proton dissociation constants for the carboxylic group and the protonated
amino group are pK1(-COOH)=2.35, and pK2(-NH3+)=9.87, respectively.
(a)What is the isoelectric point for a compound like the amino acid alanine?
In other words, explain the isoelectric point.
(b)With the above acid-base equilibrium constants, derive and calculate the
isoelectric point for this amino acid in water.
2.For 1 mole of ideal gas at 298K, calculate its total kinetic energy of the
gas molecules.
3.(a)For 1 mole of ideal gas undergoing a reversible isothermal expansion form
the initial state of (P1,V1) to a final state of (P2,V2), calculate the work
and heat the system generates in this process. The system temperature is set
at T.
(b)If a free expansion instead of the reversible isothermal expansion was
carried out in(a), calculate the accompanied work and heat in this process.
4.The mass percentage of dry air is approximately 75.5% for nitrogen, 23.2%
for oxygen, and 1.3% for argon. What is the partial pressure of each gas
when the total pressure is 1 atm? To calculate the mole fractions use
densities of 28.02, 32.0, and 39.9 g mol^-1 for nitrogen, oxygen, and argon
respectively.
5.The carbon dioxide gas actually follows the van der Waals equation with the
van der Waals constants a=3.6 L^2 atm mol^-2 and b=0.043 L mol^-1. Assuming
a temperature of 298 K and a volume of 25L, calculate the pressure of 1 mole
of carbon dioxide gas.
6.Consider the combustion reaction of the hydrogen gas:
H2(g) + 1/2 O2(g) ←→ H2O(g)
With the help of the related thermodynamic data listed below, answer the
following questions:
(a)Calculate △S°, and △H°of this reaction at 298K and a constant
pressure of 1.00 atm.
(b)Calculate △S°,and △H°of this reaction at 1000K and a constant
pressure of 1 atm.
(c)Calculate the theoretical maximum temperature that could be reached by
igniting a mixture of 1 mole of hydrogen and 0.5 mole of oxygen under 1 atm
constant pressure (i.e. a hydrogen-oxygen flame or burner). The initial
system temperature is 298K. (Hint: use Hess's law to set up a working
reaction path)
(d)The same question as in (c), except that we ignite a mixture of 1 mole
of hydrogen and 2.5 mole of the air under 1 atm constant pressure (i.e. a
hydrogen-air flame). The air consists of 20% of oxygen and 80% of nitrogen
(in mole fraction), and the initial system temperature is 298K.
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Related thermodynamic data:
(i)Molar heat capacities at constant pressure (J/mol．K)(Assuming that
they are constant over the temperatures we considered):
H2(g)=28.9 O2(g)=29.5 N2(g)=29.0
H2O(g)=24.8 H2O(l)=75.2
(ii)Thermodynamic data at 298K
Substance △H°f △G°f S°
(kJ/mol) (kJ/mol) (J/K．mol)
H2(g) 0 0 131
O2(g) 0 0 205
H2O(g) -242 -229 189
H2O(l) -286 -237 70
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7.A sealed 1-L glass container at 1 atm and 25℃ is heated and breaks when the
internal pressure reaches 2 atm. When it breaks what is the temperature
inside and what is the internal energy? Assume that the specific heat of air
has the value of Cv = 25 J/(K．mol).
8.Consider two blocks of copper with the same mass M. Assuming that one of
them is at a temperature of Tc and the other at Th with Th > Tc. The
constant pressure molar heat capacity is represented by Cp. what is the
total entropy change when these two blocks of copper are brought together
and are in thermal equilibrium with each other?
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Some equations and constants:
(i)van der Waals equation: (P+a/V^2)(V-b) = RT
(ii)1L．atm = 24.2 cal;
1cal = 4.18J;
R = 0.082 L atm deg^-1 mol^-1 = 8.31 J K^-1 mol^-1
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※ 編輯: zoe0901 來自: 140.112.5.49 (10/31 22:08)