课程名称︰普通化学丙 课程性质︰系定必修 课程教师︰陈振中 开课学院： 开课系所︰生物环境系统工程学系 考试日期（年月日）︰2008/4/24 考试时限（分钟）：10:20~12:10 (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 : General Chemistry Mid-term Examination ---------------------------------------------------------------- You may or may not find the following equation and physical constants useful. o -ΔG /RT Ｋeq = e 1atm = 101325 Pa -1 -1 Gas constant = 8.314 JK mol ---------------------------------------------------------------- Section A (25 points): 1. Salicylic acid is used in the synthesis of aspirin. One gram dissolves in 460mL of water to create a saturated solution with a pH of 2.40. (a) What is the final pH of a saturated solution that is also 0.238 M in sodium salicylate? (b) What is the final pH if 10.00 mL of 0.100 M HCl is added to 150.0 mL of the buffered solution prepare in (a)? (c) What is the final pH if 10.00 mL of 0.100 M NaOH is added to 150.0 mL of the buffered solution prepared in (a)? 附图(应该一样吧) http://commons.wikimedia.org/wiki/Image:Salicylic_acid_chemical_structure.png o 2. Consider the reaction R(aq) ←→P(aq). Given that the ΔG of this reaction is zero. (a) Calculate the Keq constant for the eaction. (b) Sketch the variation of the free energy (G) as a function of the concentration pf R. [Hints:Consider x-axis as the concentration of R, o o y-axis as the free energy. You must label the positions of Ｇp,ＧR and the equilibrium position.] Section B (75 points): 1. Which of the following is the Zeroth law of thermodynamics? A. Energy can never be created of destroyed but it can be changed from one form to another. B. Two bodies in thermal contact are at thermal equilibrium with each other if the two bodies are at the same absolute temperature. C. Any process carried out in several steps, the overall ΔH is equal to the sym of the enthalpy changes(signed) for the individual steps. D. None of the above. 2. Which of the following is an extensive property? A. Temperature B. Entropy C. Molar heat capacity D. Specific heat capacity. 3. For any spontaneous chemical reactions in a beaker at constant temperature and pressure, which of the following condition must be satisfied? A. ΔSsystem ≧ 0 B. ΔH-TΔSsystem < 0 C. ΔG ≧ 0 D. ΔSuniverse < 0 4. In an exothermic reaction, if we double the amount of reactants, which of the following statements if correct? A. The amount of heat evolved will be double. B. The amount of heat absorbed will be the same. C. The final temperature will be two times higher. D. The amount of heat evolved will be the same. 5. Which of the following has the largest entropy at room temperature? A. One mole of He atoms. B. One mole of CO molecules. C. One mole of CO2 molecules. D. 10g of liquid water. 6. Which of the following reaction is NOT favored by the system entropy? A. H2(g) + Br2(g) → 2HBr(g) B. 2H2(g) + O2(g) → 2H2O(g) C. H2O(l) → H2O(g) D. None of the above 7. Consider a mineral salt perovskite MgSiO3.If some fo the Si are substituted by Al, determine the value x for the resultant non-stoichiometrc perovskite compound MgSi0.95Al0.05Ox. A. 2.9 B. 2.95 C. 2.975 D.3 8. Which of the following equation is the correct can der Waals equation? A.[P(obs)-a(n/V)^2](V+nb)= nRT B.[P(obs)+a(n/V)^2](V+nb)= nRT C.[P(obs)+a(n/V)^2](V-nb)= nRT D.[P(obs)-a(n/V)](V+nb)= nRT 9. Referring to the following diagram, initilly the pressure and volume of the gas system is P1 and V1, respectively. What is the work done by the gas system when the ass is changed in the following way: M1→M1/2→M1/4→0 A. 0.75P1V1 B. -0.75P1V1 C.-P1V1 D. -1.16P1V1 10. The best laboratory vacuum system can pump down to as few as 1.0x10^9 molecules per cubic meter of gas. Calculate the corresponding pressure, in atmospheres, assuming a temperature of 0℃. A. 3.8x10^-14 atm B. 3.8x10^-12 atm C. 3.8x10^-17 atm D. 1.0x10^-9 atm 11. If the half life of a reaction with respect to a reactant concentration is 0.693/k, what is the reaction order of the reactant? A. First order B. Second order C. Third order D. Zero order 12. Given that a saturated NaCl solution has a concentration of 5.4M, which of the following conduction will cause NaCl to crystallize? [NaCl(molar mass 58.44); NaNO3 (molar mass 85.00)] A. Addition of 1 M NaNO3 solution to 5.4M NaCl solution. B. Addition of 10 g of NaCl crystals to 100 ml of 3 M NaCl solution. C. Addition of 6 M NaNO3 solution to saturated NaCl solution. D. Addition of 1.0g of NaNO3 crystals to 10.0 ml of 4.4 M NaCl solution. 13. The compound 2-germaacetic acid (GeH3COOH), is an unstable weak acid. At 25*C, a 0.05M solution of 2-germaacetic acid has a PH of 2.42. Determine the Ka of 2-germaacetic acid. 14. For a [H+] concentration of 0.02040 M, the PH value should read A. 1.69036 B. 1.6904 C. 1.690 D. 1.69 15. The amino acid glycine, H2N-CH2-COOH, can undergo the following equilibria in water: + H2N-CJ2-COOH + H2O ←→ H2N-CH2-COO¯ +H3O Ka = 4.3x10^-3 + H2N-CH2-COOH + H2O ←→ H3N-CH2-COOH + OH¯ Kb = 6.0x10^-5 What is the equilibrium constant for the intramolecular proton transfer + to form a zwitterions (H2N-CH2-COOH ←→ H3N-CH2-COO¯)? A. 2.6x10^7 B. 2.58x10^-7 C. 0.014 D. 2.18x10^-3 --

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