课程名称︰普通化学甲上
课程性质︰化工系必修
课程教师︰蔡蕴明
开课学院：理学院
开课系所︰化学系
考试日期（年月日）︰2020/1/8
考试时限（分钟）：110
试题 :
1. Describe in brief the second law of thermodynamics related to chemical
reactions. (5%)
2. Ammonium nitrate (NH4NO3) dissolves spontaneously and endothermically in
water at room temperature. What can you deduce about the sign of ΔS for
this solution process? Explain your answer. (5%)
3. The following diagram shows the structure of fully protonated glutamic
acid and the corresponding pKa values.
O O
∥ H2 H2 H ∥
HO─C─C─C─C─C─OH ←─pKa=2.19
↑ │
│ NH3 ←─pKa=9.67
│ +
pKa=4.25
(a) What is the PI value of glutamic acid? (3%)
(b) Running an electrophoresis experiment in a buffered solution with
pH=7.4, will glutamic acid move toward the positive or negative
electrode? Explain your answer. (2%)
4. Consider the titration of 40.0 mL of 0.200M HOCl (Ka=3.50e-8) with 0.100M
KOH. Calculate [H+] after the following volumes of KOH have been added.
(a) 40.0 mL (2%)
(b) 80.0 mL (3%)
5. Kf for the complex ion Ag(NH3)2 + is 1.7e7, Ksp for AgCl is 1.6e-10.
Calculate the molar solubility of AgCl in 1.0M NH3. (10%)
6. Calculate Ksp for iron(II) sulfide given the following data:
FeS(s) + 2e- → Fe(s) + S 2-(aq) ξ°=-1.01V
Fe 2+(aq) + 2e- → Fe(s) ξ°=-0.440V (10%)
7. Consider the galvanic cell based on the following half-reactions:
Au 3+(aq) + 3e- → Au(s) ξ°=1.50V
Tl+(aq) + e- → Tl(s) ξ°=-0.34V
(a) Calculate ΔG° and K for the cell reaction at 25℃. (6%)
(b) Calculate ξcell at 25℃ when [Au 3+]=1.0e-2M and [Tl+]=1.0e-4M (4%)
8. Consider the process
A(l) at 75℃ → A(g) at 155℃
which is carried out at constant pressure. The total ΔS for this process
is known to be 75.0 J．K^(-1)．mol^(-1). For A(l) and A(g), Cp values are
75.0 J．K^(-1)．mol^(-1) and 29.0 J．K^(-1)．mol^(-1), respectively, and
are not dependent on temperature.
(a) Calculate ΔH_vaporization for A(l) at 125℃ (its boiling point). (7%)
(b) Calculate ΔG_vaporization for A(l) at 125℃. (3%)
9. The equilibrium constant for a certain reaction decreases from 8.84 to
3.25e-2 when the temperature increases from 25℃ to 75℃. Calculate ΔH°
and ΔS° for this reaction. (10%)
10. A sample of 2.00 moles of H2 (Cv=20.5 J．K^(-1)．mol^(-1)) at 25℃ and
1.50 atm undergoes a reversible adiabatic compression until the final
pressure is 4.50 atm. Assume that the gas behaves ideally, calculate the
final volume, w, ΔE, ΔH, and ΔS. (15%)
11. Knowing S° of H2 to be 131 J．K^(-1)．mol^(-1).
(a) Calculate the entropy of 2.00 moles of H2 at 25℃ and 1.50 atm. (5%)
(b) Calculate ΔG for question 10. (5%)
12. The following table listed the molar enthalpy of combustion for several
alkanes. Predict the molar enthalpy of combustion for cyclohexane. Show
your rational. (5%)
Name Formula Structure ΔH°comb(kJ/mol)
──────────────────────────────────
Pentane C5H12 CH3(CH2)3CH3 -3.509
Hexane C6H14 CH3(CH2)4CH3 -4.163
Heptane C7H16 CH3(CH2)5CH3 -4.817
Octane C8H18 CH3(CH2)6CH3 -5.471
H2C─CH2
／ ＼
Cyclohexane C6H12 H2C CH2 ?
＼ ／
H2C─CH2