※ [本文转录自 NTU-Exam 看板] 作者: backslide (我..人很差......) 看板: NTU-Exam 标题: [试题] 彭旭明 普化甲 93上期中 时间: Sat Nov 13 19:52:54 2004 课程名称︰普通化学甲 课程性质︰ 课程教师︰彭旭明 开课系所︰ 考试时间︰2004.11.12 18:30~20:50 试题 : 1. The common names and formulas for several substances are given below. What are the systematic names for these substances? (8%) a. sugar of lead Pb(C2H3O2)2 e. milk of magnesia Mg(OH)2 b. blue vitriol CuSO4 f. gypsum CaSO4 c. quicklime CaO g. laughing gas N2O d. Epsom MgSO4 h. White vitriol ZnSO4 2. Chloral hydrate (C2H3Cl3O2) is a drug formerly used as a sedative and hypnotic. It is the compound used to make "Mickey Finns" in detective stories. (10%) Ⅰ. a. Calculate the molar mass of chloral hydrate. b. How many moles of C2H3Cl3O2 molecules are in 500.0g chloral hydrate? c. What is the mass in grams of 2.0*10^-12 mole chloral hydrate? d. How many chlorine atoms are in 5.0g chloral hydrate? e. What mass of chloral hydrate would contain 1.0g Cl? f. What is the mass of exactly 500 molecules of chloral hydrate? Ⅱ. If only chlorine consists of two isotopes, 75% 35Cl and 25% 37Cl. What would be the distribution of parent peak for chloral hydrate in mass spectrum? 3. In a given experiment with a test engine, gasoline (assume the average composition is C8H18) and air undergo combustion according to the following equation: a C8H18(l) + b O2(g) —→ c CO2(g) + e CH4(g) + f H2(g) + gH2O(g) The exhaust gas (products) was found to have the following composition (by volume): 11.5% CO2, 4.4% CO, 1.5% H2, 0.5% CH4, and 82.1% N2. These measurements were made after all the water vapor had been removed. Assuming that the N2 goes through the engine unchanged and that air consists of 21 mole percent O2 and 78 mole percent n2, determine the values of the coefficients as accurately as possible. (10%) 4. How would you separate the following ions in aqueous solution by selective precipitation? (8%) a. Ag+, Ba2+, and Cr3+ b. Ag+, Pb2+, and Cu2+ c. Hg2 2+ and Ni2+ 5. A 10.00-ml sample of vinegar, an aqueous solution of acetic acid (HC2H3O2) ,is titrated with 0.5026M NaOH, and 16.58 ml is required to reach the endpoint. (8%) a. What is the molarity of the acetic acid? b. If the density of the vinegar is 1.006 g/cm3, what is the mass percent of acetic acid in the vinegar? 6. A mixture contains only sodium chloride and potassium chloride. A 0.1586-g sample of the mixture was dissolved in water. It took 22.90 ml of 0.1000M AgNO3 to completely precipitate all the chloride present. What is the composition (by mass percent) of the mixture? (6%) 7. A series of solutions known to contain one or more of the following constituents was titrated with 0.100N base: HCl, H3PO4, and NaH2PO4. The data shown below give the volumes (mL) of reagent required to reach an end point at pH 4 to 5 (product Nah2PO4) and pH 9 to 10 (product Nah2PO4) when 25.0 mL aliquots were titrated. Calculate the composition of each solution in molarity (M). (15%) Ka1=7.5*10^-3 Ka2=6.2*10^-8 Ka3=4.8*10^-13 a. 10.2 and 20.4 b. 10.2 and 10.2 c. 10.2 and 30.7 d. 0.0 and 19.1 e. 20.2 and 27.6 8. Consider separate 1.0-L samples of O2(g) and He(g), both at 25。C and the same pressure. Compare the change in momentum per impact and the number of impacts per second in the two samples. (8%) 9. Calculate the intermolecular collision frequency and the mean free path in a sample of helium gas with a volume of 5.0-L at 27。C and 3.0atm. Assume that the diameter of a helium atom is 50 pm. Collision rate (per second) = Z = [2^(1/2)](N/V)(d^2)[(πRT/M)^(1/2)] (8%) 10. The density of a pure gaseous compound was measured at 0.00。C as a function of pressure to give the following results: Density (g/L) Pressure (atm) ------------------------------------------- 0.17893 0.2500 0.35808 0.5000 0.53745 0.7500 0.71707 1.000 Calculate the molar mass of this compound, corrected for any nonideal behavior of the gas. Assume the nonideal gas obeys the equation PV/nRT = 1 + βP. (R = 0.08206 L atm K^-1 mol^-1) (10%) 11. An important reaction for the commercial of hydrogen is CO(g) + H2O(g) ←→ H2(g) + CO2(g) (Exothermic) How will the equilibrium position shift in each of the following cases? (5%) a. Gaseous carbon dioxide is removed. b. Water vapor is added. c. The pressure is increased by adding helium gas. d. The temperature is increased. e. The pressure is increased by decreasing the volume of the container. 12. At 207。C, Kp = 0.267 atm for reaction PCl5(g) ←→ PCl3(g) + Cl2(g) (8%) a. If 0.100 mol of PCl5(g) is placed in an otherwise empty 12.0-L vessel at 207。C. calculate the partial pressure of PCl5(g), PCl3(g), and Cl2(g) at equilibrium. b. In another experiment, the total pressure of an equilibrium mixture is 2.0 atm at 207。C. What mass of PCl5 was introduced into a 5.00-L vessel to reach this equilibrium position? 13. Arrange the following 0.10M solutions in order from most acidic to most basic: CaBr2, KNO2, HClO4, and NH4NO2 (5%) 14. The equilibrium constant Ka for the reaction [Fe(H2O)6]3+(aq) + H2O(l) ←→ [Fe(H2O)5(OH)]2+(aq) + H3O+(aq) is 6.0*10^-3. (9%) a. Calculate the pH of a 0.10M solution of [Fe(H2O)6]3+. b. Calculate the pH necessary for 99.90% of the iron(Ⅲ) to be in the form [Fe(H2O)6]3+. c. Will a 1.0M solution of iron(Ⅱ) nitrate have a higher or lower pH than a 1.0M solution of iron(Ⅲ) nitrate? Explain. 15. Mix equal volumes of one solution from Group Ⅰ with one solution from Group Ⅱ to achieve the results below. Calculate the pH of each solution. (12%) Group Ⅰ: 0.20M NH4Cl, 0.20M HCl, 0.2M C6H5NH3Cl, 0.2M (C2H5)3NHCl Group Ⅱ: 0.20M KOI, 0.20M NaCN, 0.20M KOCl, 0.20M NaNO2 Ka for HNO2 = 4.0*10^-4, Ka for [(C2H5)3NH]+ = 2.5*10^-11, Ka for HOI = 2*10^-11 a. the solution with the lowest pH. b. the solution with the highest pH. c. the solution with the pH closest to 7.00. --

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