课程名称︰普通化学甲上 课程性质︰暑修 课程教师︰刘如熹 开课学院：理学院 开课系所︰ 考试日期（年月日）︰2009/07/28 考试时限（分钟）：180 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 pH of a solution that is 0.60M HF and 1.00M KF. (10%) 2. Describe how you could separate the ions in each of the following groups by selective precipitation. (8%) a. Ag+, Mg2+, Cu2+ b. Pb2+, Ca2+, Fe2+ c. Cl-, Br-, I- d. Pb2+, Bi3+ 3. A buffer is made using 45.0 mL of 0.750M HC3H5O2 (Ka=1.3*10^-5) and 55.0 mL of 0.700M NaC3H5O2. What volume of 0.10M NaOH must be added to change the pH of the original buffer solution by 2.5%? (10%) 4. Consider 2.00 mol of a minatomic ideal gas that is taken from state A (PA=2.00 atm, VA=10.0 L) to state B (PB=1.00 atm, VB=30.0 L) by two different pathways: (VC=30.0 L,PC=2.00 atm) ↗ ↘ State A (VA=10.0 L, PA=2.00 atm) State B (VB=30.0 L, PB=1.00 atm) ↘ ↗ (VD=10.0 L, PD=1.00 atm) Calculate q, w, △E, and △H for both pathways. (10%) 5. What is the difference between △H and △E at constant P? (2%) 6. Consider a sample cintaining 5.00 mol of a monatomic ideal gas that is taken from state A to state B by the following two pathways: Pathway one: PA=3.00 atm 1 PC=3.00 atm VA=15.0 L ==========> VC=55.0 L 2 PB=6.00 atm ==========> VB=20.0 L Pathway two: PA=3.00 atm 3 PD=6.00 atm VA=15.0 L ==========> VD=15.0 L 4 PB=6.00 atm ==========> VB=20.0 L For each step, assume that the external pressure is constant and equals the final pressure of the gas for the gas for that step. Calculate q, w, △E, and △H for each step, and calculate overall values for each pathway. Explain how the overall values for the two pathways illustrate that △E and △H ate state functions, whereas q and w are path functions. (20%) 7. The standard enthalpy of formation of H2O(l) at 298 K is -285.5 kJ/mol. Calculate the chanhe in internal energy for the following precess at 298 K and 1 atm: H2O(l) => H2(g) + 1/2 O2(g) △E=? (10%) 8. When water is supercooled, it freezes at a temperature below 0.0 C. If 10.9 kJ of heat is released when 2.00 mol of supercooled water at -15.0 C freezes. Calculate the molar enthalpy of fusion for ice at 0.0 C and 1 atm. Assume the molar heat capacities for H2O(s) and H2O(l) are 37.5 J/K*mol and 75.3 J/K*mol, respectively, and are temperature independent. (10%) The following choose the only one answer. 9. Which one of the following statements is false? (5%) A) The change in internal energy, △E, for a process is equal to the amount of heat absorbed at constant volume, qv. B) The change in enthalpy, △H, for a process is equal to the amount of heat absorbed at constant pressure, qp. C) A bomb calorimeter measures △H directly. D) If qp for a process is negative, the process is exothermic. E) The freezing of water is an example of and exothermic reaction. 10.Which of the following statements is correct? (5%) A) The internal energy of a system increases when more work is done by the system than heat is flowing into the system. B) The internal energy if a system decreases when work is done on the system and heat is flowing into the system. C) The system does work on the surroundings when an ideal gas expands against a constant external pressure. D) All the statement are ture. E) All the statement ate false. 11.Which statement is true of a process in which 1 mol of a gas is expanded from state A to state B? (5%) A) When the gas expands from state A to state B, the surroundings are doing work on the system. B) The amount of work done in the process must be the same, regardless of the path. C) It is not possible to have more than one path for a change of state. D) The final volume of the gas will depend on the path taken. E) The amount of heat released in the process will depend on the path taken. 12.Two metals of equal mass with different heat capacities are subjected to the same amount of heat. Which undergoes the smaller change in temperature? (5%) A) The metal with the higher heat capacity. B) The metal with the lower heat capacity. C) Both undergo the same change in temperature. D) To determine this, you need to know the initial temperature of the metals. E) To determine this, you need to know which metals you are talking about. --

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