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chem 102 old exam 2

chem 102 old exam 2 - afiflmq A Note There are 20...

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Unformatted text preview: afiflmq A Note: There are 20 questions — 1 hour Useful Information: gas constant B = 0.0820 l-atm-K“1~Inoi“1 = 8.314 J K‘l-mol‘]L Avogadro’s number No : 6.023X1023 Ideal gas law: PVanT osmotic pressure: H = MRT 760 torr = 1 atmosphere 2 760 mm Hg Raoult’s law: P A = XA P94 Arrhenius law: MT) 2 A0 exp {Ea/RT) Integrated rate laws: first order, 1n [A] = in [A9] - kt second order, 1 / [11] : kt + 1/ [A0] pH = - logm [11+] Henderson-Hasselbalch eq. pH "2 pKa + logw [base] / [acid] Kn X Kb : KW = 10‘14 quadratic formula: 1: z [—b i (b2 - 4ac)1/2 ] / 2a K. =1H+1 13-) / [HA1 K. = [33+] [011*] / [B1 Blank scratch paper for calculations etc. Will be provided by the proctors. Do not use {any Papers of your own. .12 (0. 50 mol) and Brg (0. 50 mol) were placed in a 1. 00 L flask and allowed to reach equilibrium. At equilibrium the flask contains 0. 84 mol of 1131:. What 18 the value of ? 1"“ - .. _,.. K for the reaction below gébg“; “Qt____;. \ <13 ‘ 3. 12(3) + Brfig) a 21Br(g) . A) 2.8 B) l]. C) 4_0 ‘ [U110 E) 6.1 ,-_ fr . :5” a.» 2. {go}: 3, M23 :13; ‘3...) (H A \ guru \) \ a , V9 / Q _ J; 3K) 5%}! 5% ‘ <=é3§~gn 35-13) L; ‘\ (2‘) 3‘” ._ k "3% -. la: b {El-A) 2. The equilibrium constant for reaction (1) is K. What is the equilibrium constant for equation (2)? (1) (1/3)N2(s) + PMs) \=‘ (2/3)NH3(s) (2) 2 NH3{g) re N2(g) ‘l' 3 H2(g) f A) -K3 B) K3 C) 3 K D) K/3 in)? 1/K3 3. At a certain temperature, a flask at equilibrium contains 0.0551 M 1101, 0.112 M C12, and 0.105 M H2. What is the value of Kc for the equilibrium: 2 1101(3) at 012(3) + 112(3)? A) 0.213 B) 1.63 X 10-5 C) 11.0 ’13) 3 87 E) 0.253 4. What is the [11+] in moles/ liter in an aqueous solution at 25" C Whose pH is 8.11 ‘? A) 3 12 x 10-8 B) 7.76 x 10—9 C) 1. 31 x 108 D) 7.76 X 109 B) 1 31 x 10*8 1 Consider the reaction of hydrogenation of benzene to cyclohexane: CeHan) + 3 H2(g) # C6152(0) When 1. 00 mol CEHS and 3. 00 mol H2 were placed in a 200. 0 L container and allowed to reach equilibrium over a catalyst at an elevated temperature, the resulting mixture contained 0.137 mol 05-ng. What is the equilibrium amount (moi) of H2 ? The initial amount of (351112 was zero. ._\ Lavage B) 0.137 C) 0.411 D) 0.0457 {1111)3259 {:1 bf: 52} i ”3:111; _?— risk 5: {1' 1_ '9‘"?! 1...“. . “-33:11 11.131. .: 11111.: ‘3: ”6-: Consider the following equilibrium at 500° C : 2 803(3) 14- 2 802(0) + 02(g) KC : 3.46 x10-10 A 1.0~L flask is charged with 0.10 moi 303. What will the concentration (in moi/L) of 02 be when equilibrium has been achieved? Q 0. 0000000006 6:21 L2?” (=1 5“" QB): 0. 000095 . Q g C) 0. 000120 \ 1.11 111: D) 0.000259 ‘ . E) 000000017 ,_ 11.111... “*1" 1 1 2... "3 J . 1211;: 1. “1.. _ 5&2“ 7. What is the pH of an aqueous solution at 25° C in which [11+] is 0.0025 M? A) +2.25 B) +3.40 @4129) D) —2.60 E) —3.40 This is version 3 of the exam 8. Which one of the following pairs % be mixed together to form a buffer solution? .1 ‘12:),71131004, KH2P04 “*B)...NH3, NH4CI \G)“ NRCQH302, HG]. D); RbOH, HBr ' E). ,KOH, HF 9. What are the [OH’] and pH of a 0.035 M KOH solution at 25° C ? A) 2.9 x 10*”, +1254 B) 0035, +1.40 C) 0.035, -140 a. ‘1 i, 7' 5.21.9. L3, :_ 1 33-52 62: I \‘ fl .. 1.,- a: . , 5;) L»: ‘ x" J . as»: a x: D) 2.9 x 1003,1254 5 RE): 0.035, +1254 10. The conjugate acid of H80; is A) Hsog B) so: @H2804 0) H801 s) H+ 11. The K, of H010 is 3.0 X 10—8. What is the pH at 25° C of an aqueous solution that is 0.020 M in HClO? A) +4.61 B) +2.45 C) —2.45 D) -9.22 E) +9.22 .. \A, {in ' 1,3 ’ ii ,3? ... i. \ 5.: 0 - ~ Q "‘1,“ whats: 12. KC, for HF is 7.0 x 10—4. What is K5 for the fluoride ion ? A) 1.4 x 103 B) 2.0 x 10,-8 00114 x 10~11 D) 7.0 x 10*18 E) 7.0 x 10-4 13. The K, for formic acid (HCHOg) is 1.8 X 10—4. What is the pH of a 0.35 M solution of sodium formate (NaCHOg)? .- mud-N“ v.5. A) 4.20 B) 10.71 C) 5.36 D) 3.29 $0.01,. ‘__ C: if: i,.‘ ”:31, it” 992:, .2: U W) H a; 3.3;, in; 14.2.33” , 1- {—‘K __‘ I ( G v (:1 $.J .20 r C . "‘” ii a. r i f i 14. What is the molar solubility of Mg0204? (K5? for MgCQO4 is 8.6 X 104’) A) 6.4 x 10‘13 -.]3)‘j7:9.3 x 10"3 444-4. 4-4 ) 2.8 X 10‘2 D) 4.4 x 10‘2 ) 7.0 x 10'-9 41(1- ., “L 015'. Consider a solution containing 0.100 M fluoride ion and 0.126 M hydrogen fluoride. What is the concentration of fluoride ion after addition of 5.00 mL of 0.0100 M HCl to 25.0 mL of this solution ? A) 000253 B) 0.0850 0) 0.00167 D) 00980 E):‘=0.0817 M Si: 4.44% \50 0 "‘7. 0:7“ if; . \‘Qfifr ' ‘ 0i ‘ x i ‘8‘"? A: 16. The Kb of ammonia is 1.8 X 10—5. What is the pH of a buffer prepared by combining 50.0 mL of1.00 M ammonia and 50.0 mL of 1.00 M ammonium nitrate ? A) 7.00 '13) 463 @215. D) 4.74 E) 9.37 a ., 11'. Consider the titration of 50 0 mL of 0. 217 M hydrazoic acid (HNg, KG 1. —2 6 x 10 5) I With 0.183 M NaOH Calculate the pH of the solution after addition of 70.0 mL of N: 1.4.7 NaOH solution. _ . 7"'“““- 4 1' L {:7 71731.3- :7. 7w“ \0 A) 7.00 B) 2.61 01341.97 ‘41)):1221 E) 4. 59 ‘ 047 t4 ~7< :41; 0x a .. 4 V '7 7w \ > 4 674’ w ‘3- 7 4'7 ‘ .0741 ...~44 *4 7.; V 3” iii? 1.32 . 2. <4 i 4'4““? 18. An initial pH of 4.00, an equivalence point at pH 9.35, and a moderately short, nearly vertical middle section correspond to which type of titration curve ? 8Inb)»weal< base titrated by weak acid :32}: strong acid titrated by strong base :0)»strong base titrated by strong acid 4.13.7) weak acid titrated by streng base “ E). weak base titrated by strong acid 19. 5 mL of 0.01 M HF is titrated with 0.05 M NaOH. What is the pH at the equivalence poigtjmgKa for HF is 6.8 x 10-4) 507.55 B) 7.00 C) 10.03 D) 3.17 E) 2.00 . . a . 3.7. .m- ’ E ‘ = f v _- ,- '1 . - { If“; ., (11,-7.2; 8.; ~ 1:: 2 Cy ’h- 1 - : “ 1 .* -.. ‘- .__ -- - ‘ - 1 \ti : 7 i 1 :1 x 3-...) ‘ \&l L i E. .4 U. 1: v -\_\ 4» Y i Z - '\ “7' k K? r‘ em ‘ _. a. y. , } 't \ L9 x i .- \ }_ ,. x ‘r 1 ‘00.: v ‘7 ’ .. .2“ t . :0 K”?! L “-. " {it-‘51; If 1L? 6 ‘L g . "J i \ a W‘ a!“ w- . \ Q. E ”2-. ‘ n . g i . . .mr 1., i ._ 20. What is the maximum concentration (in M) of chloride gigs in a solution that contains . 0.100 M Pb++. The K522, for leadfli) chloride is 1.0 x 10'"? A 1.0 x 10-4 141300.058 C)““0.-029 13ft): 010 fiow NIH \x; .. ’ . ,. NF 4"" .3: . ,1 if" _,.I ...
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