课程名称︰普通化学甲上 课程性质︰系订必修 课程教师︰郑淑芬 开课学院：工学院 开课系所︰化工系 考试日期（年月日）︰2009.1.14 考试时限（分钟）：110分钟 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : Single Choice Questions: (20%, 2 points per question) 1.The vapor pressure of water above 40mL of water in a 100mL container is 23.8 Torr at 25°C. What is the vapor pressure of the water if the volume of the container is changed to 50mL? (a) about 50 Torr (b) 47.6 Torr (c) 11.9 Torr (d) about 20 Torr (e) 23.8 Torr 2. Why is the vapor pressure of cis-dibromoethene lower than the vapor pressure of trans-dibromoethene? (a) ion-diple forces (b) London forces (c) hydrogen bonding (d) ion-ion forces (e) dipole-dipole forces 3.Which of the following is likely to have the larger exothermic hydration enthalpy? (a) Sr2+ (b) Na+ (c) Mg2+ (d) Ca2+ (e) Li+ 4.Which of the following has the lowest standard molar entropy? (a) C(graphite) (b) P4(s) (c) S8(s) (d) C60(s) (e) C(diamond) 5.Which of the following is always true for a spontaneous process at constant temperature? (a) ΔSsys + ΔSsurrounding = q/T (b) ΔSsys ＞ 0 (c) ΔSsys = q/T (d) ΔSsys + ΔSsurrounding ＞ 0 (e) ΔSsys ＜ q/T 6.The phase diagram of sulfur is given below: (这画不出来= =) Which of the following is true? (a) Sulfur has 2 triple points (b) Monoclinic sulfur does not sublime (c) Rhombic sulfur cannot be directly converted to liquid (d) Monoclinic sulfur is denser than rhombic sulfur (e) Rhombic sulfur, monoclinic sulfur, and liquid sulfur can exist in equilibrium at 151°C, 1300atm 7.Which of the following has the lowest freezing point? (a) 2.0m sodium perchlorate (b) 1.0m aluminum sulfate (c) 1.0m potassium phosphate (d) 1.5m magnesium phosphate (e) 1.5m aluminum nitrate 8.At 600°C, Kc=2.8 for the recation 2HgO(s)→2Hg(l)+O2(g). Calculate Kp at 600°C for this reaction (a) 6800 (b) 200 (c) 1.4×10^4 (d) 2.8 (e) 138 9.Consider the reaction 3Fe(s)+4H2O(g)→4H2(g)+Fe3O4(s) If the volume of the reaction is reduced, (a) the equilibrium constant increases (b) more H2(g) is produced (c) more H2O(g) is produced (d) more Fe(s) is produced (e) no change occurs 10.Estimate the pH of 1.0M Na2HPO4(aq) given pKa1=2.12 pKa2=7.21, and pKa3=12.68 for phosphoric acid (a) 12.68 (b) 9.94 (c) 7.40 (d) 4.67 (e) 2.12 Single Choice Questions: (30%, 3 points per question) 11.Calculate the vapor pressure at 25°C of a mixture of benzene and toluene in which the mole fraction of benzene is 0.650. The vapor pressure at 25°C of benzene is 94.6 Torr and that of toluene is 29.1 Torr (a) 84.4 Torr (b) 124 Torr (c) 71.7 Torr (d) 61.5 Torr (e) 61.5 Torr 12.Estimate the enthalpy of vaporization of CCl4 given that at 25°C and 58°C its vapor pressure is 107 Torr and 405 Torr, respectively. Assume that the enthalpy of vaporization is independent of the temperature. (a) 486 J/mol (b) 48.6 kJ/mol (c) 142 kJ/mol (d) 3.98 kJ/mol (e) 33.1 kJ/mol 13.The temperature of 2.00 mol Ne(g) is increased from 25°C to 200°C at constant pressure. Calculate the change in entropy pf neon (assume ideal behavior) (a) +7.68 J/K (b)-19.2 J/K (c)+19.2 J/K (d) +9.60 J/K (e) -7.68 J/K 14.Calculate the standard entropy of cindensation of chloroform at its boiling point, 335K. The standard molar enthalpy of vaporization of chloroform at its boiling point is 31.4 kJ/mol. (a) -31.3 kJ/K‧mol (b) +31.4 kJ/K‧mol (c) +93.7 J/K‧mol (d) +506 J/K‧mol (e) -93.7 J/K‧mol 15.Calculate ΔSsurr° at 298K for the reaction 6 C(s)+3 H2(g)→4 C6H6(l) ΔHr° = +49.0 kJ/mol, ΔSr° = -253 J/K‧mol (a) +164 J/K‧mol (b) -164 J/K‧mol (c) -417 J/K‧mol (d) -253 J/K‧mol (e) +253 J/K‧mol 16.Estimate the minimum temperature at which magnetite can be reduced to iron by graphite. FeO3(s) + 2 C(s) → 2 CO2(g) + 3 Fe(s) ΔSr° = +351.44 J/K‧mol. The standard molar enthalpies of formation of magnetite and CO2(g) are -1118.4 and -393.51 kJ/mol, respectively. (a) 670°C (b) 787°C (c) 943°C (d) 1790°C (e) Magnetite cannot be reduced by carbon at any temperature 17.Calculate ΔG at 298K for the recation C2H5OH(l) → C2H5OH(g,0.0263bar) given ΔG°=6.2 kJ at 298K (a) 6.2 kJ (b) 15 kJ (c) 2.8 kJ (d) -2.8 kJ (e) -15 kJ 18.If ΔG°=27.1 kJ at 25°C for the recation CH3COOH (aq) + H2O (l) → CH3COO- (aq) + H3O+ (aq) what is Ka for this recation at 298K? (a) 1.15×10^-11 (b) 5.63×10^4 (c) 1.78×10^-5 (d) 1.01 (e) 9.89×10^-1 19.Consider the recation 2 Fe2O3 (s) + 3 C (s) → 4 Fe (s) + 3 CO2 (g) ΔH°=462 kJ ΔS°=558 J/K Calculate the equilibrium constant for this recation at 525°C. (a) 3.04×10^-3 (b) 1.9×10^6 (c) 8.07×10^-2 (d) 2.18×10^-2 (e) 5.20×10^-7 20.The pH of 0.10M pyridine(aq) is 9.13. What is the value of Kb for pyridine? (a) 2.7×10^-4 (b) 7.4×10^-10 (c) 2.7×10^-5 (d) 1.8×10^-10 (e) 1.8×10^-9 Descriptive & Calculating Questions 21.Account for the differences in basic strength of the following compounds. NH2 NH2 NH2 │ │ │ ╱ ＼＼ ╱ ＼＼ ╱ ＼＼ ∥ ∣ ∥ ∣ ∥ ∣ ╲ ╱╱ ╲ ╱╱ ╲ ╱╱ ∣ ∣ Cl OH pKb= 9.37 9.85 5.47 (6%) 22. (a) Calculate q,w,ΔU,ΔH,ΔS,ΔG associated with the isothermal expansion of 5.65 mol of ideal gas from 22.32 atm to 13.04 atm at 358K (not reversible process) (10%) (b) What is ΔSsurr in this expansion? (2%) 23.A 2.50% by mass MgSO4(aq) solution has a freezing point of -0.325°C (a) Estimate the van't Hoff i factor from the data. (b) Determine the total molalities of all solute species. (c) Calculate the percentage dissociation of MgSO4 in this solution. (10%) 24.Pysozyme is an enzyme that breaks bacterial cell walls. A solution containing 0.150g this enzyme in 210 mL of solution has an osmotic pressure of 0.953 torr at 25°C. What is the molar mass of this substance? (5%) 25.Draw "on the same figure" the "phase diagrams" of (10%) (a) water , (b) 0.1M NaCl solution , and (c) 0.1M surcrose solution Indicate (i) the phases (ii) the normal boiling point (iii) the normal freezing point and (iv) the triple point. 26.Consider the titration of 25.0 mL of 0.100M NH3 with 0.100M HCl solution. (Kb of NH3 = 1.80×10^-5) (a)Calculate the pH values after the following volumes of HCl have been added: 0mL ; 5.0mL ; 1.0mL before the equivalence point ; at the equivalence point ; 1.0mL after the equivalence point ; and 5.0mL after the equivalence point. (18%) (b)Draw the titration curve. (3%) (c)What is the pKa range of the indicator which will be needed? (2%) --

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