课程名称︰分析化学一 课程性质︰必修 课程教师︰张焕宗 开课学院：理学院 开课系所︰化学系 考试日期（年月日）︰2009.10.26 考试时限（分钟）：10:10am~13:00pm 是否需发放奖励金：是~Danke （如未明确表示，则不予发放） 试题 : I. Fill in the blanks (45pts,3pts each) 1. Write down the autoprotolysis of acetic acid:__________ 2. The ionic strength of 10mL of 0.2M AgNO3 aqueous solution after adding 10mL of 0.1M NaCl is ________ 3. Write down the mass-balance equation when dissolving Hg2Cl2 in 0.01M NH3. Solubility=[Cl-]=_____________ 4. The solubility of AgCl (Ksp=10^-11) in 0.5M NH3 is ________ if the formation constant for Ag(NH3)2+ is 10^8. 5. If the pH is 7.3 after titrating 20mL of 0.1M H2A solution with 30mL of 0.1M NaOH, a possible pKa1 value for H2A is _______ ±1. 6. If 10mL and 15mL of 0.1M NaOH solution are needed to titrate a solution to pH 3.7 and 8.3, the acidity of the solution is _______ 7. The concentration of I- is ______ after 0.1M NaI solution was added to selective precipitation of one of the metal ions in a solution containing 0.001M Pb2+ and Hg2+. (Ksp value for PbI2 and Hg2I2 are 7.8*10^-9 and 4.6*10^-29, respectively) 8. Arrange the decreasing order of the acidity of the following solution (each 0.1M):_________________ (1) HCOOH (2) CF3COOH (3)phenol (4) o-hydroxybenzoic acid (5) p-hydroxybenzoic acid 9. Write down at least three species of aqueous solution containing Al3+ ions : ____________ 10. Arrange the decreasing order of the acidity of the following aqueous solution (each 0.1M): Na+,Ca2+,Fe2+,Fe3+,NH4+ : _________________ 11. Arrange the decreasing size of the ions Li+,Na+,K+,Mg2+, and Al3+ in aqueous solution : ______________ 12. A 0.50mL aliquot of protein solution was digested, and the liberated NH3 was distilled into 10.00-mL of 0.02M HCl. The unreacted HCl requires 3.00-mL 0.02M NaOH for complete titration. If the protein contains 16.2% nitrogen (14.00g/mol), the concentration of protein is ______ mg/mL. 13. The pH values of 0.04M H2L+ and L- are ________ and _________, respectively. At pH ____, [H2L+]=[L-]. K1 and K2 are 4.70*10^-3 and 1.80*10^-10, respectively. II. Comparison:(20pts,4pts each) 1. Volhard and Fajans titration 2. Amphiprotic species and zwitterion 3. Isoelecrtric and isoionic point 4. Blank titration and standardization 5. Quantitative analysis and qualitative analysis III. Acids and bases (76pts) 1. Derive the relationship between [H+] and K1, K2, and K3 when 0.1 mol Na2HPO4 is dissolved in 1-L water. (Ka1:1.1*10^-2 ; Ka2:7.5*10^-8 ; Ka3:4.8*10^-13) (6pts) 2. Derive the fractional composition equation of αHA2- with [H+],K1 ,K2, and K3. (6pts) 3. Derive Va*10^pH = (γB/Ka*γBH+)*(Ve-Va) (6pts) 4. What kind of information is provided from Gran plot? (4pts) 5. Roughly plot a fractional composition diagram of 0.1M Na2HPO4. (6pts) 6. Calculate the pH value after adding 20, 25, 30, 40, 55, and 60mL of 0.1M HCl to 20mL of 0.1M Na2HPO4 solution. (12pts) 7. Plot a titration curve. (4pts) 8. What are the major and second most species after adding 25 and 55mL of 0.1M HCl to 20mL of the solution? (8pts) 9. What are the concentrations of HPO42- at pH values of 3.0, 6.0, and 7.0, respectively? (6pts) 10. Define buffer capacity of a buffer solution? (4pts) 11. Under what conditions, the buffer bears a good buffer capacity? (4pts) 12. How can you prepare a 0.1M phosphate buffer of pH 7.00? (Assume that the formal concentration of phosphate species is 0.1M) (6pt) 13. What are the pH changes after separately adding 10.00mL 0.1M NaOH and 0.1M HCl to 10.00mL of the buffer? (4pts) IV. Activity and solubility (28pts,4pts each) 1. Explain the equation logγ= -0.51*(z^2)*(μ^1/2)/[1+(α*(μ^1/2))/305]. 2. Why does the solubility of CaCO3 increase upon increasing NaNO3 concentration? 3. At the same concentration of the electrolytes, write down the decreasing order of the solubility of CaCO3 in the solutions of 0.1M NaNO3, Mg(NO3)2, and Al(NO3)3. 4. The solubility of CaCO3 in water. (Ksp = 4.5*10^-9; αCa2+ = 600pm; αCO32- = 400pm) 5. The solubility of CaCO3 in water containing 0.1M NaNO3. 6. The solubility of CaCO3 in water at pH 9.0 (K1 and K2 for H2CO3 are 4.46*10^-7 and 4.69*10^-11, respectively; neglect the activity) 7. The solubility of CaCO3 in water at pH 4.0. (neglect the activity) V. Analtysis of catechins in tea. (20pts, 4pts each) ---------------------------------------------------------------------------- Catechins, which are types of flavonoids, are among the most interesting biologically active compounds that are present at relatively higher concentration in green tea leaves and, at lower levels, in grape seeds, wine, and persimmons. The five major catechins known to display biological activity are (+)-catechin, (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCG), and (-)-epicatechin gallate (ECG). Catechins exhibit numerous potentially beneficial medicinal properties, including inhibition of carcinogenesis, tumorigensis, and mutagenesis. In addition to catechins, green tea also contains amino acids, caffeine, and ascorbic acid. Among free amino acids, theanine (1-glutamyl-γ-ethylamide) is the predominant amino acids in green tea. Many analytical methods have been developed to determine these important tea components, including thin layer chromatography (TLC), gas chromatograghy (GC), reverse-phase high- performance liquid chromatography (HPLC), capillary zone electrophoresis, micellar electrokinetic chromatography, and microemulsion electrokinetic chromatography. ------------------------------------------------------------------------- Based on what you learn from Chapter 0 of the textbook and the above sentences, answer the following questions: 1. Why is it important to determine the concentration of catechins in tea? 2. Write down all general steps in the chemical analysis of catechins in tea (Names of the steps are enough). 3. Does sampling affect the final results? 4. How can you determine the concentration of catechin if HPLC is selected? 5. How can you ensure that your final results are right (reasonable)? VI. Biopolymers:(24pts, 4pts each) 1. Suggest a method to determine the pI value of a protein? 2. Suggest a technique for proteomics. 3. Are the pI values of transferrin and apotransferrin the same? Why? 4. Suggest a method to determine the concentration of Fe3+ in transferrin. 5. Why does the activity (biological function) of most enzymes depend on the pH and ionic strength of solution? 6. Why are DNA sample usually prepared in TBE buffer? ================================================================ total: 213 points --

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