Shandong University Physical Chemistry(2)Quarter Exam-1 2020-2021 Aoadommio Year Fall Semester 号国國五六[七九团十分分人 (A)H2+ 12-2HI is an elementary reaction; B)H2+12-2HI is a complex reaction, 2020-2021 Academic Year. Fall Semester (C)H2+1-2HI is a bimolecular reaction, The First Quarter Exam of Physical Chemistry(2) D)The partial ord IS [1-5]For branched chain explosion, there are three explosion limits, P, P, and p. The All constants can be found in Yin Y J, Physical Chemistry, P. 438 existance of pz limit is )The more collision of radical with container wall 舞兽人 (C)The higher thermal conductivity, 2 L. Choose the best answer for the following questions(4 points for each [I-6] Among the following photophysical processes, which can send out fluorescence [l-1) For an exothermal reaction, its equilibrium yield is 25% at 400 K. When a catalyst is (A)Sa-S, internal conversion; (B)S-TI intersystem crossing. introduced, the equilibrium can be achieved in the same time at 300 K. Then the equilibrium → So decay, yield will be 舞分舞卷人 (A)Higher than 25% (B) less than 25%, 封 (C) Equal to25%‰ (D)uncertain. IL. Fill the blanks(4 points for each blank, totally 24 points) [1-2] For the following statements of rate constant, which is not correct? [2-1]A reaction takes place according to the following mechanism (A)Rate constant is the proportional factor in rate lav A+B一C+D (B) Rate constant depends on temperature and pressure, (C) For reaction with different reaction order, the unit of rate constant is different; F+B-2A+G Then the stoichiometric equation of the overall reaction is [-3] For following reactions, the activation energy of which is the second highest? Given that DH -h= 436 k mol-It DcLc 243 kJ mol-l, DH ce 431 kJ me (A)CCl→→2Cl [2-2] For reaction 21-+H2Or-12+H2O, its experimental rate law is (B)Cl+HH→→Hl+H dH,O,I [rJH, O, (C)H*ClCl→→HCl+Cl The mechanism is proposed as follow (D)2Cl+M→Cl+M [1-4The experimental rate law of H2+ 12-2HI isr=AHi[]. What conclusion can we (D)1+H2O2-10+H2O reach from this experiment L +Ho 第1页共2
2020-2021 Academic Year Fall Semester 题号 一 二 三 四 五 六 七 八 九 十 总分 总分人 得分 2020-2021 Academic Year, Fall Semester The First Quarter Exam of Physical Chemistry (2) ---------------------------------------------------------------------------------------------- All constants can be found in Yin Y. J., Physical Chemistry, p. 438 得分 阅卷人 I. Choose the best answer for the following questions (4 points for each question, totally 24 points) [1-1] For an exothermal reaction, its equilibrium yield is 25% at 400 K. When a catalyst is introduced, the equilibrium can be achieved in the same time at 300 K. Then the equilibrium yield will be (A) Higher than 25%; (B) less than 25%; (C) Equal to 25%; (D) uncertain. [1-2] For the following statements of rate constant, which is not correct? (A) Rate constant is the proportional factor in rate law; (B) Rate constant depends on temperature and pressure; (C) For reaction with different reaction order, the unit of rate constant is different; (D) Rate constant is independent of concentration of reactants. [1-3] For following reactions, the activation energy of which is the second highest? Given that DH—H= 436 kJ mol-1；DCl—Cl= 243 kJ mol-1 , DH—Cl= 431 kJ mol-1 . (A) Cl⎯Cl ⎯→ 2Cl; (B) Cl + H⎯H ⎯→ H⎯Cl + H; (C) H + Cl⎯Cl ⎯→ H⎯Cl + Cl; (D) 2Cl + M ⎯→ Cl2 + M. [1-4] The experimental rate law of H2 + I2 ⎯→ 2HI is r = k[H2][I2]. What conclusion can we reach from this experiment? (A) H2 + I2 ⎯→ 2HI is an elementary reaction; (B) H2 + I2 ⎯→ 2HI is a complex reaction; (C) H2 + I2 ⎯→ 2HI is a bimolecular reaction; (D) The partial order of H2 is 1. [1-5] For branched chain explosion, there are three explosion limits, p1, p2, and p3. The reason for the existance of p2 limit is (A) The more collision of radical with container wall; (B) The existance of impurity; (C) The higher thermal conductivity; (D) The gaseous terminating is dominant. [1-6] Among the following photophysical processes, which can send out fluorescence (A) S2⎯→S1 internal conversion; (B) S1⎯→T1 intersystem crossing; (C) S1⎯→S0 decay; (D) T1⎯→S0 decay. 得分 阅卷人 II. Fill the blanks (4 points for each blank, totally 24 points) [2-1] A reaction takes place according to the following mechanism: A + B C + D 2C F F + B 2A + G ⎯⎯→ ⎯⎯→ ⎯⎯→ Then the stoichiometric equation of the overall reaction is ____________________. Substance A is _____________. [2-2] For reaction 2I− + H2O2⎯→I2 + H2O, its experimental rate law is 2 2 2 2 [H O ] - = [I ][H O ] d k dt − The mechanism is proposed as follow. (1) I − + H2O2⎯→IO− + H2O (2) 2H 2 2 IO I I H O + − − + ⎯⎯⎯→ + Shandong University Physical Chemistry (2) Quarter Exam-1 College Major Grade Student No. Name … … … … … … … … … … … … … … 密 … … … … … … … … … … 封 … … … … … … … … … … 线 … … … … … … … … … … … … … 第 1 页 共 2 页
Shandong University Physical Chemistry(2)Quarter Exam-l 2020-2021 Academic Year Fall Semester Which is the rate-determining step, (1)or(2)? 3-21[7 points] Based the rate law of SCT, answer the following questions (2-3]The quantum yield (@)of H2+Cl gaseous reaction is about 104-106.When this(1)[3 points] List as many as possible the ways to increase the fraction of activated reaction is performed in CHCI solution with quantum yield of o, then a__@P,performed at 400 K, give explanation to their [2-4] An organic compound can be formed biologically after absorbance of 8 photon with reaction rate based on SCT and TST theories. The covalent radius and atomic mass of CI wavelength of 600 nm. The combustion enthalpy of this compound is 468.6 W mol-I. Then are 99.4 pm and 35.45, for I, they are 133 pm and 126.90; Bond energy of Cl-Cl,H, the energy efficiency is H-Cl and H- is 243, 151, 431, 298 k mol-I 分舞人 IV Calculation(totally 22 points) Ill. Answer the following questions: (Totally 30 points) 41l3 points] Saponification(皂化) reaction: 3-1[23 points For reaction CiCl+Cl-C2Cls, two mechanisms are proposed CH:COOCzHs+ NaOH- CH3COONa+ C2HsOH (1)(a)Cl2+-→C is a second-order reaction. If the initial concentration of CH3CooCzHs and NaOI (b)C2C4+C2b→C2C1 mol dm, after 600s, 39.0%CH: COOC2Hs is converted at 298.2 K. (aC2+hby→2Ck s, 55% CH: COOCzHs is converted. 封 (b)CC2+Ck→c2Cl (1)[5 points] What is the activation energy of this reaction? Eax (2)[4 points] At 288.2 K, how many CHsCOOC2Hs can be converted after 600 s? (3)14 points] How many time does it take to convert 50%o CHsCOOCzHs at 288.2K? It was found that the quantum yield of the reaction is very high. Answer the following[(+2][9 points]For competing reactions questions: [The bond dissociation energy of CI-CI bond( Dac)is 243 wJ mor- (1)A+B→C (1)(4 points] Which mechanism is correct, (1)or(2)? Why? (2)AB→→D he reaction order with respect to A and B is both I. At 300 K, when the initial (3)12 points] In order to initiate the reaction, what kind of light irradiation(wavelength in concentration of A and B is I mol dm, after 30 min of reaction, 15% of A converts to C and 25% of A converts to D (4)(2 points]If the absorbance intensity of incident light is la. Find the rate law of step(a')I(1) Calculate the ratio of kw/k, (5)16 points] Deduce the rate law from mechanism(2). (3) The activation energy of reaction(1)and (2)is Ea, I= 150 k] molland Ea? mol-, respectively. What is the apparent activation energy of the overall reaction? )( points] Show the relation between the apparent activation energy (Ea ap)and those of(4)If we want to increase the yield of C, should we carry the reaction at higher or lower the relevant elementary steps, estimate the value of Ea, app temperature? 第2页共2页
2020-2021 Academic Year Fall Semester Which is the rate-determining step, (1) or (2)? ______ [2-3] The quantum yield (1) of H2 + Cl2 gaseous reaction is about 10 4~106 . When this reaction is performed in CHCl3 solution with quantum yield of 2, then 1______2 (>, <, =). The change in quantum yield can be attributed to the ________ effect. [2-4] An organic compound can be formed biologically after absorbance of 8 photon with wavelength of 600 nm. The combustion enthalpy of this compound is 468.6 kJ mol-1 . Then the energy efficiency is ___________________. 得分 阅卷人 III. Answer the following questions: (Totally 30 points) [3-1] [23 points]For reaction C2Cl4 + Cl2 ⎯→ C2Cl6, two mechanisms are proposed. (1) 1 2 * 2 2 * 2 4 2 2 6 (a) Cl Cl (b) C Cl Cl C Cl k k + ⎯⎯→ h + ⎯⎯→ (2) ' 1 ' 2 ' 3 ' 4 2 ,1 2 4 2 5 ,2 2 5 2 2 6 ,3 2 5 2 5 2 6 2 4 ,4 (a') Cl 2Cl (b') C Cl Cl C Cl (c')C Cl Cl C Cl Cl (d')C Cl C Cl C Cl C Cl k a k a k a k a h E E E E + ⎯⎯→ + ⎯⎯→ + ⎯⎯→ + + ⎯⎯→ + It was found that the quantum yield of the reaction is very high. Answer the following questions: [The bond dissociation energy of Cl—Cl bond(DCl-Cl) is 243 kJ mol-1 .] (1) [4 points] Which mechanism is correct, (1) or (2)? Why? (2) [3 points] For mechanism (2), define the initiating, propagating and terminating step. (3) [2 points] In order to initiate the reaction, what kind of light irradiation (wavelength in nm) is required? (4) [2 points] If the absorbance intensity of incident light is Ia. Find the rate law of step (a’) of mechanism (2); (5) [6 points] Deduce the rate law from mechanism (2). (6) [2 points] What is the reaction order of the reaction? (7) [4 points] Show the relation between the apparent activation energy (Ea, app) and those of the relevant elementary steps, estimate the value of Ea, app. [3-2] [7 points] Based the rate law of SCT, answer the following questions: (1) [3 points] List as many as possible the ways to increase the fraction of activated molecules. (2)[4 points] For H2+Cl2⎯→ and H2+I2→ performed at 400 K, give explanation to their reaction rate based on SCT and TST theories. [The covalent radius and atomic mass of Cl are 99.4 pm and 35.45, for I, they are 133 pm and 126.90; Bond energy of Cl⎯Cl, I⎯I, H⎯Cl and H⎯I is 243, 151, 431, 298 kJ mol-1 ] 得分 阅卷人 IV. Calculation (totally 22 points): [4-1] [13 points] Saponification (皂化) reaction: CH3COOC2H5 + NaOH ⎯→ CH3COONa + C2H5OH is a second-order reaction. If the initial concentration of CH3COOC2H5 and NaOH is 0.010 mol dm-3 , after 600 s, 39.0% CH3COOC2H5 is converted at 298.2 K. At 308.2 K, after 600 s, 55% CH3COOC2H5 is converted. (1) [5 points] What is the activation energy of this reaction? (2) [4 points] At 288.2 K, how many CH3COOC2H5 can be converted after 600 s? (3) [4 points] How many time does it take to convert 50% CH3COOC2H5 at 288.2 K? [4-2] [9 points] For competing reactions 1 2 (1) A+B C (2)A+B D k k ⎯⎯→ ⎯⎯→ The reaction order with respect to A and B is both 1. At 300 K, when the initial concentration of A and B is 1 mol dm-3 , after 30 min of reaction, 15% of A converts to C and 25% of A converts to D. (1) Calculate the ratio of k1/k2; (2) Determine k1and k2; (3) The activation energy of reaction (1) and (2) is Ea,1 = 150 kJ mol-1 and Ea,2 = 140 kJ mol-1 , respectively. What is the apparent activation energy of the overall reaction? (4) If we want to increase the yield of C, should we carry the reaction at higher or lower temperature? Shandong University Physical Chemistry (2) Quarter Exam-1 学院 专业 级 学号 姓名 … … … … … … … … … … … … … … 密 … … … … … … … … … … 封 … … … … … … … … … … 线 … … … … … … … … … … … … … 第 2 页 共 2 页
