CHEM105b - Exam 1 (2010, Spring)b

CHEM105b - Exam 1 (2010, Spring)b - Chemistry 105 B Exam 1...

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Unformatted text preview: Chemistry 105 B Exam 1 02/04/10 Dr. Parr “ILL-1 HIE-1L5 (rm-,farfi'! fir? .r J1 .u. n. I .* V» d rial-[5-4 huw‘f _ on AW” :4"- . _' - I. gimp: . Please Sign Below: ' ' _ Instructions: 1. You must show work to receive credit. 2. There are 11 problems on 11 pages. Please count them before you begin. A periodic table and some useful equations can be found on the last page. 3. If necessary, please continue your solutions on the back of the preceding page (facing you). 4. You MUST submit all pages to the proctors, including the periodic table page. Put your name onto the periodic table page in the space provided. 5. You MUST use black or blue ink in order to be eligible for any regrades. (No whiteout, no erasable ink, no pencil.) 6. Only a Casio FX-260 calculator may be used on Chem IOSa/b exams. 7. Turn off cell phones and other electronic communication devices and put them away, out of sight. They may not be taken out of your bag during the exam. 8. When time is called, stop working on your exam immediately, pass it to the aisle. 9. Good luck! ! =) turn the exam over and \(a/iéfa/K A 1. (10 pt) For the reactioWC (g), the following data were obtained at constant tem erature: new: : KMZWET’“ {47kt Afflluita] c. If the initial concentration of A is 0.450 what is the initial rate of the reaction? Mic: K [flJGLDfiJ [Oink : .5—OC3L‘3M'til/Irun'f . What is the value of k, the rate constant, for this reaction? (Be sure to include units) Initial Rate mol/L*min / M and the initial concentration of B is 0.250 M, 2. (8 pt) Biacetyl, the flavoring that . argarine taste "mim- _ f . r butter," is extremely stable at room temperature, but 200°C t undergoes breakdown with a rate constant of 0.077 M'lmin'l. industrial flavo rocess requires that . i d initially contained 0.50 M biacetyl? a biacetyl-flavored food he heate = ' - . at 200°C. WWWvor __Wiflhe_food_is_lmted f /-’ 3 c). O77 M“'WYW" QMWV ~—-—{-— :Ké/r ’ [Al [$3 [fl 3 (007714"w'v")(3.;m)+ / d W l ~ #1 _ [7d ‘r' 9.326%” F 0. (15/1 M ' 2/ 3. ( pt) Many drugs decompose in blood bprocess. I ' secobarbital sodium, a common sedativ ° ' L e, . . mposed to 18A) - 1 smaximum concentration. What is the half—life for the secobarbital decomposition? [Sta/2am: In [fljf’zf 7‘“ (hf/log {—1 $0M: [A]:®M%X&] 0, (973 {4/} Off 7—: ' 0, bah—3’ ’él/gL ; Using the grids provided determine thefprder o is already provided on each grid. [3% MM, arr—1 *———-— / """a. J1; n51" (‘1/3:/.li+ 11hr! .m 1W m r M ,,,. a W M M r W NW W m ., m 3; f g _ 4y -..i r l L Emumumwnmw mmhumtmnummh “.mfinmnmnmmm ..m.._n..n.nmunnm fimmnmmuumummumo ) mmunuuulnmmmummm mm mmmumummmumu lune mmuuunuuuuhu- 0 _ Hui Wm“! H Hf HHi _ H HIM.” i 5 .\ / 1 l ,5 3 a Time (s) I ,_ m ,3; .L, _,__ 1%:{19411 (“(1137 73(97‘4 0’73 . @ pt) A slightly bruised apple will rot extensively in aboéy‘aat room temperature (20°C). If it is kept in the r u-‘r-v :. e at 1.0”C, the same e /,. of rotting will take about 16 days. Rotting i a first-order rocess. What is the activation energy for the rotting reaction? m / c-_———v ‘---1—'—-"‘_._...—._ ' ' J" 7,. ’ (C T: awe/aim fl/ffzréifi_ I) is, ' I“ t, ' 72101432 ml: 1 a {Ll/CW CDqu ‘l,33(o '—‘ % al.003‘7f rmaam m am: e “K (are .i 55: ( v. WWJ I . £4§¢M/o~ gl é mew? Q3; if 0'51“? r “79 .2”; \K 5’7” ’ x _ y”) / r /c .1445 . 6. (10 pt) The catalytic destruction of ozone occurs via a two—step mechanism, where can be any of several species: 7&- 03 6' XQ + 02 (slow) x03 0 —> X3 02 (fast) a. Write the overall reaction. W 03 in O a b, X acts as ‘ and X0 acts as EWCC'fia/l (file c. If t - r ' v r ' 11 energy for the forward reaction is 354 kJ/mol and the forward reaction ~ ' ' - 97 kJ/mol, what is the activation energy for the reverse 7. (9 pt) Consider the foilowing equilibrium process at 700°C: 2 H2 (9 + S; (g) H 2 H28 (3) a. Analysis shows that there are 2.50 moles of H2, 1.35 x 10'5 moles of S; and 8.70 moles of H28 present at equilibrium in a 12.0 L flask. Whtmilibfimstant (K) for this reaction? :— Qflbmf W [(75331 @£#}3 ran a ' 0" 20? M / :: “‘——‘«;“’ A 94013 [33] [3%.] 5 Wm": (. {01mm 9/4 [9, db immeaarm [0.7937431 J: : £0 .0) 053L If, mm ‘M 3 f b. At a lower temperature the equilibrium constant is 6.7. If an equilibrium mixture contains 3.5 moles of S; and 3.5 moles of H28 in a 2.5 L flask, what is the concentration of H2 in this equilibrium mixture? fie? [%J:§%?:lfi1M £173.33s trim [)MMU\ é—7: '“* i 6 @300 a? s. (9 pt) Given the following: 12 (g) H 2 I( £5 = 3.8 x 10-5, determine the equilibrium constants for the followi _ g reactions. 3.6I(g)<->312 g) -.__ 3 fluff/i) / X3 K '_" /, b. 1(3) H 1/2 12 (g) i r . iriemcet/ )L/Q‘ 0K— /ér1 C. 512(g)4->101(g) MM 9. (10 pt) Consider the reaction 2 SO; (g) + 02 (g) H 2 $032!; which is exothermic. In which direction will the reaction shift in order to restore—an equilibrium disturbed in each of the following ways. Circle the correct answer. 0? me 1 3% a. the temperature is.increased @ right no change b. the volume is decreased left @ no change c. 802 is added left no change d. a catalyst is: added left right @ e. He gas is added left right no change 10. (10 pt) Consider the decomposition of ammonium hydrogen sulfide: NH (s) H NH3 (9 + H23 0;) A 6.16 g sample of ammonium hydrogen sulfide is placed in a 4.00 L container at 240°C. After equilibrium has been established, the total pressure inside the container is 0.709 atm and some solid NH4HS remains. Nah, Hoe—Ewing) #55 O 0 +>< t)‘ 3. Determine Kp for this reaction. If C 11. (10 pt) The equilibrium constant for the reaction: H2 (8) + 12 (g) <—> 2 HI (g) is 54.3 at 430°C. At Were are 0.714 moles of H2, 0.714 moles of 12 and 0.886 moles of HI in a 1.00 L container. Calculate the concentrations of all the gases at equilibrium. H01 ti; é—~>&Hf 4/25"” 3 Tcw3a'cr7ogz: k Mr? F {0,83% at ) L a N f.— -—' W 4:" ' *1! “£2113 (mm) [0. 7114—4 JR 617/0] —&)L W 2‘; 737(0/7M-wx) 0. EKG +2o< : ., £2371 932x: m 9-37 ...
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CHEM105b - Exam 1 (2010, Spring)b - Chemistry 105 B Exam 1...

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