課程名稱︰普化甲上
課程性質︰暑修
課程教師︰劉如熹
開課學院：理學院
開課系所︰化學系
考試日期（年月日）︰98/7/31
考試時限（分鐘）：120
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
1. Calculate the change in entropy that occurs when a sample containing 2.00
mol of water is heated from 50℃ to 150℃ at 1 atm pressure. The molar heat
capacities for H2O(l) and H20(g) are 75.3JK^(-1) mol^(-1), respectively, and
the enthalpy of vaporization for wate is 40.7kJ/mol at 100℃.(10%)
2. The value of Kp is 3.7*10^(-6) at 900K for the ammonia synthesis reaction.
Assuming the value of ⊿H0 for this reaction is -92kJ, calculate the value of Kp
at 550K.(10%)
3. For mercury the enthalpy of vaporiztion is 58.51kJ/mol and the entropy of
vaporiztion is 92.92 JK^(-1) mol^(-1). What is the normal boiling point of
mercury?(9%)
4. For the reaction at 298K,
2NO2(g)←→N2O4(g)
the value of⊿H0 and ⊿S0 are -58.03kJ and -176.6J/K, respectively. What is
the value of⊿G0 at 298K? Assuming that ⊿H0 and ⊿S0 do not depend on
temperature, at what temperature is ⊿G0=0? Is ⊿G0 negative above or below
this temperature?(10%)
5. A 1.00-mol sample of an ideal gas in a vessel with a movable piston
initially occupies a volume of 5.00L at an external pressure of 5.00 atm.
a. If Pex is suddenly lowered to 2.00 atm and the gas is allowed to expend
isothermally, calculate the following quantities for the system: ⊿E,⊿H,
⊿S,⊿G⊿, w and q.
b. Show by the second law that this process will occur spontaneously.(10%)
6. Consider 1.00 mol of an ideal gas that is expanded isothermally at 25℃
from 2.45*10^(-2) atm to 2.45*10^(-3) atm in the folowing three irreversible
steps:
Step 1: from 2.45*10^(-2) atm to 9.87*10^(-3) atm
Step 2: from 9.87*10^(-3) atm to 4.93*10^(-3) atm
Step 3: from 4.93*10^(-3) atm to 2.45*10^(-3) atm
Calculate q,w,⊿E,⊿S,⊿H,and ⊿G for each step and for the overall process.
(12%)
7. Benzene(C6H6) has a melting point of 5.5℃ and an enthalpy of fusion of
10.04 kJ/mol at 25.0℃. The molar heat capacities at constant pressure for
solid and liquid benzene are 100.4 JK^(-1) mol^(-1), respectively. For the
reaction
C6H6(l)←→C6H6(s)
Calculate ⊿Ssys and ⊿Ssurr at 10.0℃.(10%)
8. The amount of manganese in steel is determined by changing it to
permanganate ion. The steel is first disssolve in nitric acid, producing Mn2+
ions. These ions are then oxidized to the deeply colored MnO4- ions by
periodate ion (IO4-) in acid solution.
a. Complete and balance an equation describing each of the above reactions.
b. Calculate ε0,⊿G0,and K at 25℃ for each reaction.
(10%)
9. Consider the galvanic cell based on the following half-reaction:
Au3+ + 3e- → Au ε0 = 1.50V
Tl+ + e- → Tl ε0 =-0.34V
a. Determine the overall cell reaction and calculate ε0 cell.
b. Calculate ⊿G0 and K for the cell reaction at 25℃ .
c. Calculate ε0 cell at 25℃ when [Au3+] = 1.0*10^(-2) M and [Tl+] =
1.0*10^(-4) M
(9%)
10. Consider the following half-reactions:
Pt+ + 2e- → Pt ε0 = 1.188V
PtCl4^2- + 2e- → Pt + 4Cl- ε0 = 0.755V
NO3- + 4H+ + 3e- → NO + 2H20 ε0 = 0.96V
Explain why platinum metal will dissolve in aqua regia(a mixture of
hdrochloric and nitic ascids) but not in either concentrated nitric or
concentrated htdrochloric acid individually. (10%)
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