课程名称︰普化甲上 课程性质︰暑修 课程教师︰刘如熹 开课学院：理学院 开课系所︰化学系 考试日期（年月日）︰98/7/31 考试时限（分钟）：120 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 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%) -- ████◤█▕▕◥████ / / █████ 医X系 48号 ████◤◣◣◣███◤ \ \ ◢██◣◣ / 我叫 █████﹀" █/ ██◤◥ / / C███▂█▌ 金珂拉 ██████ i█ ██ ═ \ \ █████ 珊‧克拉 ／ ████◣██◤ ██◣ / / ◥█▼█◤ ／ ██◤█◤██◤██◤◤█ \ \ ███ ψclassam --

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