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Exam_3_Solutions - Selma” HOUR EXAM III Version A CHEN...

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Unformatted text preview: Selma”; HOUR EXAM III - Version A CHEN 1211 . Thursday, November 18, 2010 Profs. George & Bowman 7:45PM to 8:45PM Answer 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 thoroughly. Be sure to fill in the boxes for your student number, name and lab section; then fill in the corresponding bubbles beneath them correctly. A periodic table with atomic numbers and masses is attached to the back of this exam. There are 7 exam pages and 14 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 = 6.022 x 1023 mol'1 Number of Moles = Concentration X Volume R=0.08206 liter atm mol‘1 K'1 = 8.314 J mol‘1 K‘1 1 atm = 760 mmHg = 1.01 x 105 Pa 1 J = 1 kg mzlsz 1 amu = 1.6605 x 10‘24 g Temp (K) = Temp (C) + 273 Zero-Order -d[A]/dt = k, [A] = [A]O — kt, t1 /2= [A]0 / (2k) First-Order -d[A]/dt = k[A], [A] = [A]0 e'kt, t1/2= ln2 / k Second-Order "-d[A]/dt = k[A]2, 1/[A] = 1/[A]O + kt, tug: 1 / ([A]ok) Arrhenius Equation k(T) = A exp(-Ea/ RT) 1n (P.2/P1) = (AHvap IR) (1/T1-1/T2) KP = Kc (Rom Kc =Kp (RT)'A“ pH =-log[H+] Kw = [H3O+][OH'] = KaKb = 1.0 x 10'14 Ka = [H30+][A‘]/[HA] —bi\/b2 ~4ac x = ——"""' for the quadratic equation ax2 + bx + c = 0 2a So deflfl’ 5 (5 Points) What volume of 0.284 M HN03 is required to neutralize 45.3 mL of 0.982 M KOH? M56667 46,) ;MW xQ/we E21 1:33;: V W $6M (c) 78.3mL 3/ (0 283%): <0 ?82M)(0'04$3L) (d) 157mL (e) 271mL ll A 5/5 7W4L that yields two OH‘ hydroxide ions for every Ba(OH) mo ecule. ?}/(: “if? (04:7 a . * a Eb: 1:3 1:on :: 2 a 0.3on 8% 01 c .3 . L , gm : 0 0"“ #0-»; 95 (e) 13.60 LH”) : LN ’1 32-5710 {0H ":1 ' Wt: , (if $er ’3) "‘@ (8 Points) Ammonia, N H3, has a base diss lon constant of Kb=1. 8 x 10 . the conjugate acid of ammonia and What 18 its acid dissociation constant, Ka ? ./‘\ s t. (a) NH4+, 1.9 x 109 . (b) NH4+, 1:8 _er10'5 ” NH4+, 5.6 x 10:10 (d) NHz', 5.6 x 10'“) (e) NHZ', 1.9 x 10‘5 4. (8 Points) Aspirin is a monoprotic weak acid with the formula, C9H804. A tablet of aspirin is dissolved in water to make a 0.028 M solution. Given that the Ka=3.0 x 104, what is the pH of the solution at equilibrium? 9/ Ff 67 ? C?}7'70,7 3 O O , . , j-«Y (c) 3.52 a W X 14‘ )C (d) 5.08 )q " I ’ " K f7 " (e) 6.28 I; 0 02% 2 W0»- 91.01% 3 x; e waif}: 0,3?”4 K4" “1.1. 2 t‘H/(e 2. If”: “470} (@0” 5. (10 Points) Lea - - . unit cell with an edge length of 4.95 A. 1 A = l x 10'8 cm. What is the density of lead in f“ wags 9 MSST— Wag”; ey‘u/(Q.(d_ ’— - 1 . :1, e I s—L “L W (a I : ”mm/M :- gya‘x (”3 @ 3'0”" -————X :2; X' ‘0. 0~028~x ‘ g/cm3? e ollowing statem '- - ; (5 Points) Whic o (a) London Dispersion interactions are weaker than ion-dipole interactions. Te l/UC’ (bhe - :7 0) '- .- - lid state is typically much lower than the entropy in the gas state. Tflu’i I. ssure is 1 , nerally higher and the boiling point lower for molechE 2) has larger London dispersion forces than fluorine (F2). '7’ £14 E (6) None of the Above Statements is False 7. 9. (10 Points) The boiling point of water is 100°C at a pressure of 1.0 atm. If the pressure in a pressure cooker reaches 5.0 atm, what is the boiling point of water at that pressure? The heat of vaporization of water is AHvap- — 40. 7 kJ/mol. flag?) :. A’M— 1— (a) 373 K ‘3 ”'4‘ .. #0700 WM. .1... a i- (C) 528 K a [0% I § '3)”: yww’z 373 /2 (d) 773 K § 1; t I (e) 1865K 3% x )0 : _.._ ,_, _: (5 Points) In the reaction A + 2B + 1/2 C ----> 3/2 D + 3 E, the rate of appearance of E is 3.0 moles per second. What is the rate of disappearance of C ? / 06 1?: 0— 55.. 11 = g? "e (b) 1.0 moles/s ! d ‘ 6 (c) 3.0 moles/s (d) 12.0 moles/s (e) 18.0 moles/s (5 Points) Which of the following statements about kinetics and equilibrium is true? W7 é!” - constants generally become lower-as the temperature increases. V/{i‘ §P 's ium the rates of the forward and reverse ractions are equal to each . - - ual to zero. Téi/CE’ (c) Second order reactions are always faster than first order reactions Fri/(LSE (d) For a second order reaction the half— life does lag/depend on the initial fi¢¢g é: concentration. (e) For a zero order reaction the time necessary to react away 0 of the initial » S 0 , a..- reactant is equal to one half— life. 50% flé/ 10. (10 Points) Rate constants for the production of NO from the reaction: N02(g) + C0(g) —+ N0(g) + C02(g) are 1.3 (M s)'1 at 700 K and 23.0 (M s)‘1 at 800 K. What is the value of the activation energy? k z A' W (’3’ E . 1 j 25’ O (a) 32kJ/mol £830 2 W - F4 8;; -- 731:) ,. l4 3 (b) 48 kJ/mol fl \ 25 ‘ $7 (0) 54 kJ/rnol 7“? 5" “A [77.3— " Z' - M ___,. 2', /——————” "7‘ . (d) ., 01 K a ) __ 0,00017‘} Ef_ /é/00i<’ z—DE’e" Gmfl K -- 33,400 W 11. (8 Points) For the equilibrium reaction below which has the equilibrium constant g i 3, 9; kO’ Kp = 5.0x10‘6: N2F4(g) (—9 2NF2(g) _ m {(00 703 [g 3/9“) A container is initially filled with 2.0 atm of N§F4 gas. The reaction then proceeds to equilibrium. What is the equilibrium partial pressure of NF2? . 9.5 2M4: (a) 1.0x10'5atm Nag—f z. (b) 0.0010atm 7" 120% O (c) 0.0016‘atm (d) 0.0022 atm Q ”"‘ X @5 (BX C2702 5': X _ PA/F? : 12. (8 Points) For the equilibrium reaction: N2(g) + 3H2(g) H 2NH3(g) the equilibrium concentrations are: 0.325 M for N2; 0.975 M for H2; and 1. 350 M for NH3 at 350°C. What IS the KP? {#71331 .9 i l 33 )2— V I V (a) 0.0023 K5 {H233 [ft/,3 (0.97538 (0 323) (b) 0.235 (c) 6.05 ‘ Kc ' é if (d) 2.3x103 ’5’ : K gr) : (e) 1.6x104 F C ( , 13. (10 Points) For the reaction of A 4:) 2C, an equilibrium condition finds the concentrations of A and C to be 0.050 M and 0.0070 M, respectively. If A is added rapidly to double the concentration of A to 0.10 M, what will the new concentration of C 3 be after equilibrium 1s reestablished? , [C316 05792 -1» 0 )(/O KC .. [A] (9 OS’ (a) [C] = 0.0035 M (b) [C]: 0.0070M A, 6,.) Z O [cj= 0.010M ‘ 01007 f 06/ «r Zx (d) [C] = 0.014 M (e) [C]=0.028M , C WK 5).?07f2x 7': 0"] wx 1.3 (9.007 +ZX) KQ:)“O>‘10 *‘" o'lvx‘ 14. ‘ What is the version of your exam? éggww’e x c c o. 1 z (a) VersionA __3 (a 007 9“ 2X) (b) VersionB / .« O )( / d L: ...
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