課程名稱︰普通化學甲上
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）︰98/07/31
考試時限（分鐘）：180
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 cintaining 2.00
mol of water is heated from 50C to 150C at 1 atm pressure. The molar heat
capacities for H2O(l) and H2O(g) are 75.3 J/K*mol and 36.4 J/K*mol,
respectively, and the enthalpy of vaporization for water is 40.7 kJ/mol at
100C. (10%)
2. The value if Kp is 3.7E-6 at 900K for the ammonia synthesis reaction.
Assuming the value of △H for this reaction is -92 kJ, calculate the calue
of Kp at 550K (10%)
3. For mercury the enthalpy of vaporization is 58.81 kJ/mol and the entropy of
vaporization is 92.92 J/K*mol. What is the normal boiling point of mercury?
(9%)
4. For the reaction at 298K
2NO2(g) <=> N2O4(g)
the values of △H and △S are -58.03 kJ and -176.6 J/K, respectively. What
is the value of △G at 298K? Assuming that △H and △S do not depend on
temperature, at what temperature is △G = 0? Is △G 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 5.00 L 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 25C from
2.45E-2 atm to 2.45E-3 atm in the following three irreversible steps:
Step 1: from 2.45E-2 atm to 9.87E-3 atm
Step 2: from 9.87E-3 atm to 4.93E-3 atm
Step 3: from 4.93E-3 atm to 2.45E-3 atm
Calculate q, w, △E, △S, △H, and △G for each step and for the overall
precess. (12%)
7. Benezene (C6H6) has a melting point of 5.5C and an enthalpy of fusion of
10.04 kJ/mol at 25.0C. The molar heat capacities at constant pressure for
solid and liquid benzene are 100.4 J/K*mol and 133.0 J/K*mol, respectively.
For the reaction
C6H6(l) <=> C6H6(s)
Calculate △Ssys and △Ssurr at 10.0C (10%)
8. The amount of manganese in steel is determined by changing it to
premanganate ion. The steel is first dissolved in nitric acid, prodicting
Mn2+ ions. These ions are then oxidized to the deeply colored MnO4- ions by
preiodate ion (IO4-) in acid solution.
a. Complete and balance an equation describing each of the above reactions.
b. Calculate ε, △G, and K at 25C for each reaction. (10%)
9. Consider the galvanic cell based on the following half-reactions:
Au3+ + 3e- ==> Au ε = 1.50 V
Tl+ + e- ==> Tl ε = -0.34 V
a. Determine the overall cell reaction and calculateε cell.
b. Calculate △G and K for the cell reaction at 25C
c. Calculate ε cell at 25C when [Au3+] = 1.0E-2M and [Tl+] = 1.0E-4M
(9%)
10.Consider the following half-reactions:
Pt2+ + 2e- ==> Pt ε = 1.188 V
PtCl42- + 2e- ==> Pt +4Cl- ε = 0.755 V
NO3- + 4H+ + 3e- ==> NO + 2H2O ε = 0.96 V
Explain why platinum metal will dissolve in aqua regia ( a mixture of
hydrochloric and nitric acids) but not in either concertrated nitric or
concentrated htdrochloric acid individually. (10%)
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