CHEN1211Fall07Test3

CHEN1211Fall07Test3 - HOUR EXAM III - Version A CHEN l211

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Unformatted text preview: HOUR EXAM III - Version A CHEN l211 W’ednesda‘efievewbenibfi 94m... . Profs. George & Bowman Ellill‘M to 8:00PM .»-‘\nswer all questions on the scantron answer sheet by filling in the proper bubble with a number 2 pencil. If you change your answer. please erase the undesired mark lhnrouglih; Be sure to fill in the boxes for your student number, name and lab section; then iii! in the corresponding bubbles beneath them correctly. A periodic tabic with atomic numbers and int-isses is attached to the back of this exam. ""‘ "r nere are: exam-pages'a'xfuub‘questions. The last question asks for the version of your exam. Check to be sure you have answered all the questions. Please note the point values of each question. Useful Information: Avogadro's Number 2 6.022 x 1023 111101"1 Number of Moles = Concentration x Volume R=0.03206 liter atm moi" K" = 8.314 J mol" K" 1 atm = 760 mmHg = 1.01 x105 Pa 1 J = 1 kg mzfsz - 1 amu = 1.6605 x 10'24 g Temp (K) = Temp (C) + 273 Zero—Order -d[A]fdt = k, [A] = [A]0 - kt, t1 ,2: [A10 ; (2k) First-Order —d[A]fdt = k[A], [A] = [A]0 e-kt, t] a: 1112 r k Second-Order -d{A]fdt = k[A]2, not] = 1.1.41.3 + kt, 121/2: 1 x ([A]0k) Arrhenius Equation k(T) = A exp(-Eaf RT) 111115311 L: fifl-hvap’mffi’fi 111915 K. = Kc (Rotn K. = K, (RUM pH = -10s[H+] Kw : [H30+][OH‘] = KaKb = 1.0 x 10"4 K3 = [H3 0+][A'1/ [HA] “biVbz -4ac x = W for the quadratic equation 3x2 + bx + c = 0 2a g: (c) Molecules with strong intermolecular forces typically exhibit ighefivapor pressures ‘ (10 Points) Carbon tetrachloride is a solvent that has a vapor pressure of 100.0 mm Hg at 23 °C and has a heat of vaporization of 32.3 kamol. What is the normal boiling point of carbon tetrachloride? P; N E “VI-fl / “L r J- x) I “M W “H”: —-—- I'm—'- rgu, 47°C M: ;- l l”: to“ I b 25 °C -_ ( ) o a .. 3- _ J— (c) 41 C wig 295a”. ,x’ (d) 54 C‘C , . 124....‘2953 “\(e) 77 C Us“. 1 _ r __I _L T. i a - .. — T 2— «in; h ‘o a e ,3? _ q; self-p 4?..- _.._.‘;’.__'.1.._','.‘._;'__._;.m....:ata..Lw ? 2 it... . , 535’“! J’rjr“.*"-”’ (8 Points) Which of the followmg statements 15 FALSE? ( f: (a) Ion-Dipole interactions are typically stronger intermolecular forces than dipole- dipole interactions. (b) The entropy in the liquid state is typically higher than the entropy in the solid state. .. ~~.. in _ and boiling points. 1’ Iii'x- (d), Theentrony; in thelidpid. and. solidstatesafi'resshrail‘hm'enmmy‘nrbieg‘assmre. __ i I I r e), H sirlmggn bonding" rs‘lypreclhyptnmger‘hmF meuonrfirspers 1m 1‘ ntremdirons. . x if C.) (10 Points) The packing efficiency in two dimensions is defined as the percentage ofthe area in the unit cell occupied by atoms. For the two—dimensional face-centered cubic (FCC) unit cell shown below, what is the packing efficiency? The area of a circle representing each atom in the two dimensional plane is equal to It r2. — i 1 n ,5: - (qr) :- dag... _ _ JVW...‘ . . a ""’ “" “x ; ;.- . - . .r (a) 93.2% is.- a. \ 2 H,- g: l... Ill—:l. a| ... ( “FT!” [l$l}_3,l73.5% ' - " {f' r. {I \XH J/r 'd/ (6) 7130/0 2: a"? Jl— I; J (if 1 I”. a.“ _ f.» ---.H-\. n _.f_ -~.__ {I}: (d) 53.9% r- ,9: I/ .7! . \ - ..'.- g? I ....W.I'.....w. ._ | a a a l - t it ~ . (c) 39...) A] 3 my p a in, d 2 \ —r’-/ (if \\R-— // it P.- ;. - . 3! 4..., We cf: 0 r1 ‘1}. J 227‘“ 4. (7 Points) In the reaction A + 2B + HZ C nu} 32 D + 4 E, the rate of appearance of E is 50 moles per second. What is the rate of disappearance of C ? _I_ are: 5:. air; @ 0.62 molesfs ‘f' {a} f c?! 1"- (b) 1.25 molesr’s a: L r _L 5 p N) f M n f (e) 2.5 molesfs 5E? '55:.- 5’ E"— ' 0- 6“- E“ (d) I 0.0 molcsfis (e) 40.0 molesfs U! (10 Points) Water in a swimming pool evaporates with zero-order kinetics -d[i120] f dt = kJHoflJf wheres A: (L. F1429] jisotheo‘ujtal'hfisl mass' 1n‘tne svvimnimg poor. 'I‘I‘nafr'tne water from the pool evaporates in 24.0 days, how much time is required for 2J3 ofthe water to evaporate? f1 5;" 5-:- iii“ 32-0 days x a; ’60 (b) 36.0 days '- :i — Kc; ("LI/r; 4?, 3e/ k‘ u“ _J' (c) 37.5 days A r " - ' (d) 40.0 days .2- {its} .. r;- (6) 48.0 days 3 A -- ._ ,5" (5:51.: _ _. .4 .: L. (8 Points) The reaction of N3(g) + 3 Hg(g) <—> 2NH3(g) has an equilibrium constant Kc= fiflfiafifi ’L. Tfilflrnidienfi‘fugflflmnlresifi'lifanfif‘efi‘u‘nnlrcsifi‘Nhg'are initially placed in a 1.0 liter container at 25°C, what is the reaction quotient, Q? Will the reaction go to the left or right as the system reaches equilibrium? a,_. 7 ' "a f ’ . '- _,-h:: u'. “‘1’ 3: (a) Q=0.50,right Q:— I a. k h: w. _: O ../'~ . -. ' - r - 2:;- g .,L_'-f ”‘ ‘ er- ‘7? @ Q=0.25, right a. fit:- O “2;.- (c) 0:050, left Q < K: :: 6,09 (d) Q=0.25, left {3%, g 9 h grief ([9) (e) Q=0.125, right " {8 Points}, The thermal dissociation of qhosqhorous qentaatilmi ilJ’b:Tb"glV’El1L1)y+h?c reaction PCls(g) <—-> PCl3(g) + Clg(g). This reaction has an equilibrium constant Kp=1.78 at 523 K. What is KG for this reaction at 523 K? (a) 634 PC’Se—f PC’3*C’2— am”! ,- F43 f“: (b) 76.4 a} 2 Mp (T RT) .- I f L W} ’- -;. _.I F (0)1'78 :: {.75 0,03206 k x 55’ e l) 4.15 x 10'2 w a. (c) 5.27x10'3 = 4.11?th (‘3) (8 Points) When baking soda is heated it decomposes according to the following reaction: 2N3HCO3(S) <—) Na2C03(s) +H20(g) + C02(g) 'ff sufficient baking soda is placed in a container and heated to 90°C, the total pressure of the gases is 0.5451 atm. What is the value of K9 at that temperature? . P + “r:- f‘ ’ -- "' "'- c twi)?‘ 0.07423 K P m Page 5, a t, a?" was; ,_ (b) 0-2973 _ _ . - a... p, .- _ (C) 04228 KI: W ('53.: 7'2; 2‘»? f ‘ (d) 1.091 =- 7, ‘4 x ’0 l 3* a; a? Fears 5.61:?” (c) 5.088 3' 62M??? l " H K a. (, / ' 0,272 51+». a m f 2?; A 5" kiwi: 2‘ x“ 6' 7 3r X :- R’ {5'1 x‘deg {Riff mfg. [RIO-7 :. 2x 2 {.006 xiv | IL, . mi PDifltSL,PD1Lthfi- followinqgeactinn -the.in.itial..cnncem.r.ations-ofi broth?! ’m i ‘al’id‘uz are 0.15 M and Kc : 4.5 x 10'“. What is the concentration of NO when the system reaches equilibrium? N0 N0 is present in the initial mixture. N2(g)+ 02(g) <-> 2N0(g) (a) 0-50 x 10'” M .... 1.0 x1046 M I O (c) 2.0x 10'16 M «3 V (d) 2.6x 10*" M 2x -16 <6) 10 M a.-- 3'5. -- x ll. (7 Points) Milk has a hydroxide ion concentration of [OH'] = 2.0 x 10'7 M. What is the . 4 L71 pH of milk? Is milk acidic or basic? , e3; i" and; :__ is a): .- 3. r a: 3 (up 1 .....M. w 7 J g. [’9 _..~ I. H . -' “Ly-I (I. .I I“. :3 (3) PH 3 6.70, acidic L» -' ... r” (to, sit... amach up is? «2.. _,, if ,1 7 3w I) (C) pH = 7.30, acidic w" {L’- ._ R3,. pH = 7.30, basic (e) pH = 7.70, basic 12. (8 Points) Which of the following statements concerning acids and bases is FALSE? (a) The Arrhenius definition of an acid is a compound that produces H+ ions. . ' ' ' . " . , m .- . a..." i" S in 4:3 The stronger the ac1d, the®gierhts conjugate base. I“ be}. w fill-:1 fl [P (c) The reaction ofa strong acid and a strong base produces H20 and a salt. ‘, : H L“) (d) A Bronsted-Lowry base is a substance that can accept H+ ions. (e) The equilibrium constant for H20 dissociation is Kw = [H+][OH']= 1.0 x 10'14 at room temperature independent of whether the solution is acidic or basic. 13. What is the version of your exam? Version A (b) Version B ...
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This note was uploaded on 05/01/2008 for the course CHEN 1211 taught by Professor Gin,doug during the Fall '08 term at Colorado.

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CHEN1211Fall07Test3 - HOUR EXAM III - Version A CHEN l211

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