Name Chemistry 153-080 (3150:153-080) EXAM II Multiple-Chice Prtin Instructins: Tuesday, 5:10PM FORM A March 18, 2003 120 1. Each student is respnsible fr fllwing instructins. Read this page carefully. 2. Write yur name n this page and n yur cmputer answer sheet. 3. CODE yur name (LAST NAME FIRST) n the cmputer answer sheet using an rdinary (N. 2) pencil. It is very imprtant t cde the infrmatin crrectly!! 4. Put all calculatins n the examinatin pages. D nt make any extra marks n the cmputer answer sheet!! 5. This part f the exam cnsists f 15 multiple-chice questins wrth 8 pints each. Fr each multiplechice questin, chse the ONE best r crrect answer and write it bth n yur exam paper and n the answer sheet. The cmputer answer sheet is the nly ne that will be graded fr the multiple-chice prtin f the exam! 6. This exam bklet cnsists f 4 pages (including this ne) and a Peridic Table and Frmula/Data Sheet. Please check t be sure that yu have them all! KEEP YOUR EXAM BOOKLET AND ANSWER SHEET COVERED TO PROTECT THE INTEGRITY OF YOUR WORK! Blimp Mania!!
1. 2. 3. 4. Which f the fllwing statements is FALSE? (a) Entrpy is a measure f a driving frce behind chemical reactins. (b) Entrpy is a measure f disrder r randmness. (c) Entrpy can be created and destryed. (d) Entrpy is a measure f the number f ways energy can be distributed amng the mtins f particles. (e) Entrpy is a measure f the tendency f energy t becme less cncentrated. Chemical thermdynamics predicts (crrectly) that materials made f wd, paper, metal, plastic, leather, and rubber react with xygen in the atmsphere and decmpse at 25 C and 1 atm pressure. Which f the fllwing is respnsible fr the fact that these reactins are very slw under these cnditins? (a) entrpy (b) enthalpy (c) internal energy (d) activatin energy (e) ptential energy The fllwing equatin represents the reactin that ccurs when fuel il and ammnium nitrate, a cmpnent f fertilizer, react explsively. This kind f explsin destryed the Murrah Federal Building in Oklahma City, Oklahma in 1995. 52 NH 4 NO 3 (s) + C 17 H 36 (l) 52 N 2 (g) + 17 CO 2 (g) + 122 H 2 O (g) Using psitinal entrpy arguments, the S sys fr this prcess wuld be: (a) psitive (b) negative (c) zer (d) It is impssible t tell. The fllwing equatin was derived fr the [H 3 O + ] in a slutin f a weak acid in water: [H O ] = K C + 3 A acid 5. 6. What assumptins were included in the derivatin f this frmula? I. there are n OH ins present in the slutin. II. the aut-inizatin f water is negligible. III. [H 3 O + ] is much smaller than C. acid (a) I nly. (b) II nly. (c) III nly. (d) II and III nly. (e) I, II, and III. Frmic acid (HCOOH) is a weak acid with K A = 1.8 10 4. Acetic acid (CH 3 COOH) is a weak acid with K A = 1.8 10 5. Which f the fllwing is/are TRUE? I. Frmate in (HCOO ) is a strnger base than acetate in (CH 3 COO ). II. A 0.10 M slutin f frmic acid has a larger percent dissciatin than a 0.10 M slutin f acetic acid. III. Frmic acid is a strnger acid than acetic acid. (a) I nly. (b) II nly. (c) III nly. (d) I and II nly. (e) II and III nly. Additin f sdium frmate t an frmic acid slutin at equilibrium will cause: (a) n change in H 3 O + cncentratin. (b) H 3 O + cncentratin t decrease. (c) H 3 O + cncentratin t increase. (d) cncentratins f all species t increase. (e) a decrease in hydrxide cncentratin.
Use the titratin curve fr a titratin f a weak acid with 0.18 M NaOH belw fr Questins 7 8. 7. 8. The pk A f the weak acid is clsest t: (a) 1.5 (b) 3.0 (c) 4.0 (d) 4.5 (e) 8.5 The ph at the equivalence pint f the titratin is nt = 7.0 because: (a) at the equivalence pint, there is excess OH present. (b) at the equivalence pint, the slutin cntains the cnjugate base f the weak acid. (c) at the equivalence pint, the weak acid becmes a strnger base than water. (d) The ph f an equivalence pint shuld be 7.00. This titratin cntains sme experimental errr. 9. 10. Calculate the ph f a buffer prepared by mixing 0.05 ml f sdium frmate (HCOONa) and 0.10 ml f frmic acid (HCOOH) in 1.0 L f slutin. [HCOOH: K A = 1.8 10 4 ] (a) 1.8 10-4 (b) 3.44 (c) 4.05 (d) 5.31 (e) nne f these Wuld a slutin f ammnium brmide (NH 4 Br) be acidic, basic, r neither? K A (HBr) = 1.0 10 9 ; K B (NH 3 ) = 1.8 10 5. (a) acidic (b) basic (c) neither acidic nr basic
11. 12. 13. 14. 15. A reactin has a value f G = 83.9 kj. Which f the fllwing must be TRUE abut this reactin? I. The reactin is spntaneus at standard cnditins. II. 83.9 kj f wrk must be dne n the reactin t make it ccur. III. The equilibrium cnstant f this reactin is greater than 1. (a) I nly. (b) II nly. (c) I and II nly. (d) I and III nly. (e) I, II, and III. A reactin has a value f G = 83.9 kj. Hw lng (in s) wuld the reactin take t reach equilibrium? (a) 83.9 s (b) 167.8 s (c) 251.7 s (d) 42.0 s (e) It is impssible t tell. Which f the fllwing might increase the slubility f a salt abve the mlar slubility estimated frm the K SP value? (a) frmatin f in pairs (b) frmatin f cmplex ins (c) reactin f ins with water (d) all f the abve The slubility prduct cnstant fr cbaltic hydrxide, C(OH) 3, is 1.6 10-44. What is the slubility f cbaltic hydrxide in a slutin buffered at ph 9.00? (a) 1.6 10 44 M (b) 1.6 10 29 M (c) 1.3 10 22 M (d) 1.6 10 17 M (e) nne f these Which f the fllwing sets f cnditins is cnsistent with a reactin that wuld be spntaneus at LOW temperatures and nnspntaneus at HIGH temperatures? (a) H psitive, S negative (b) H psitive, S psitive (c) H negative, S psitive (d) H negative, S negative
Equatins/Cnstants/Cnversin Factrs T K = T C + 273.15 T F = (9/5) T C + 32 T C = (5/9) [T F 32] Avgadr: 6.022 10 23 R = 8.314 J/ml K R = 0.08206 L atm/ml K T B = i k B m rate = k [A] n, n=0, 1 r 2 k = Ae E /RT A K C = K P (RT) n T F = i k F m [A] =!kt + [A] E A 1 ph = lg[h 3 O + ] ln k = ln A! P A = X A PE A ln[a] =!kt + ln[a] R T + [H T F = T 3O ] = K ACacid F T F 1 1 = kt + + T B = T [A] [A] B + T k2 EA 1 1 [H3O ] = K W+ K ACacid B ln = _ ln([a] / [A] k F fr water = 1.86 ) =!kt k1 R T2 T1 [OH ] = K BCbase C/m k B fr water = 0.512 C/m _ ln([a] / [A]) = kt [OH ] = K W+ KBCbase K W = [H + ][OH ] = 1.00 10 14 at 25 C HSYS G = RT ln K G = nfe S ph + poh = 14.00 at 25 SURR = (at cnstant P) C T K W = K A K B [H + ] = [H 3 O + ] G = H! T S G = GE + RT ln Q HE = Σn H f (prducts) Σn H f (reactants) SE = ΣnS (prducts) ΣnS (reactants) ph = pk 1A (1) 1 H 1.008 3 Li 6.941 11 Na 22.99 19 K 39.10 37 Rb 85.47 55 Cs 132.91 87 Fr (223) A 2A (2) 4 Be 9.012 12 Mg 24.31 20 Ca 40.08 38 Sr 87.62 56 Ba 137.33 88 Ra [226] _ [A ] + lg [HA] 3B (3) 21 Sc 44.96 39 Y 88.91 71 Lu 174.97 103 Lr (260) 57 La 138.91 89 Ac [227] 4B (4) 22 Ti 47.88 40 Zr 91.22 72 Hf 178.49 104 Rf (261) 58 Ce 140.12 90 Th 232.04 5B (5) 23 V 50.94 41 Nb 92.91 73 Ta 180.95 105 Db (262) 59 Pr 140.91 91 Pa 231.04 6B (6) 24 Cr 52.00 42 M 95.94 74 W 183.84 106 Sg (263) 60 Nd 144.24 92 U 238.03 G = w MAX GE = Σn G f (prducts) Σn G f (reactants) E CELL = EE CELL! RT ln Q ln K = nfee F = 96485 cul/ml e nf RT 7B (7) (8) 25 26 Mn 54.94 Fe 55.85 43 Tc (98) 75 Re 186.21 107 Bh (262) 61 Pm (145) 93 Np [237] 44 Ru 101.07 76 Os 190.23 108 Hs (265) 62 Sm 150.36 94 Pu (244) 8B (9) (10) 27 28 C 58.93 Ni 58.69 45 Rh 102.91 77 Ir 192.22 109 Mt (266) 63 Eu 151.96 95 Am (243) 46 Pd 106.42 78 Pt 195.08 110 (269) 64 Gd 157.25 96 Cm (247) 1B (11) 29 Cu 63.55 47 Ag 107.87 79 Au 197.00 111 (272) 65 Tb 158.93 97 Bk (247) 2B (12) 30 Zn 65.39 48 Cd 112.41 80 Hg 200.59 112 (266) 66 Dy 162.50 98 Cf (251) 3A (13) 5 B 10.81 13 Al 26.98 31 Ga 69.72 49 In 114.82 81 Tl 204.38 67 H 164.93 99 Es (252) 4A (14) 6 C 12.01 14 Si 28.09 32 Ge 72.61 50 Sn 118.71 82 Pb 207.2 114 (285) 68 Er 167.26 100 Fm (257) 5A (16) 7 N 14.01 15 P 30.97 33 As 74.92 51 Sb 121.76 83 Bi 208.98 69 Tm 168.93 101 Md (258) 6A (16) 8 O 16.00 16 S 32.07 34 Se 78.96 52 Te 127.60 84 P (209) 116 ( ) 70 Yb 173.04 102 N (259) 7A (17) 9 F 19.00 17 Cl 35.45 35 Br 79.90 53 I 126.90 85 At (210) 8A (18) 2 He 4.003 10 Ne 20.18 18 Ar 39.95 36 Kr 83.80 54 Xe 131.29 86 Rn (222)
Standard Thermdynamic Values at 298 K Substance H f (kj/ml) G f (kj/ml) S (J/ml K) Substance H f (kj/ml) G f (kj/ml) S (J/ml K) Ag + (aq) 105.9 77.111 73.93 CuSO 4 (s) 769.86 661.9 113.39 AgBr (s) 99.51 95.939 107.1 Fe 2 O 3 (s) 825.5 743.6 87.400 AgCl (s) 127.03 109.72 96.11 H + (aq) 0 0 0 AgI (s) 62.38 66.32 114 HCOO (aq) 410. 335 91.6 Al 2 O 3 (s) 1669.8 1582 50.94 HCOOH (aq) 410. 356 164 Br (aq) 120.9 102.82 80.71 H 2 O (g) 241.826 228.60 188.72 C (s, diamnd) 1.896 2.866 2.439 H 2 O (l) 285.840 237.192 69.940 C 12 H 22 O 11 (s) 2221.7 1544.3 360.24 H 2 O 2 (g) 136.10 105.48 232.9 C 2 H 2 (g) 226.7 209 200.85 H 2 O 2 (aq) 191.2 134.1 144 C 2 H 4 (g) 52.47 68.36 219.22 H 2 O 2 (l) 187.8 120.4 110 C 2 H 4 (OH) 2 (l) 460.0 319.8 163.2 H 2 SO 4 (aq) 907.51 741.99 17 C 2 H 4 (OH) 2 (g) 392.2 298.2 303.8 HBr (g) 36.23 53.5 198.59 C 2 H 5 OH (l) 277.63 174.8 161 HCl (aq) 167.46 131.17 55.06 C 2 H 6 (g) 84.68 32.89 229.5 HCl (g) 92.30 95.30 186.79 C 3 H 8 (g) 103.85 24.5 269.9 HI (g) 25.9 1.3 206.33 C 6 H 12 O 6 (s) 1273.3 910.56 212.1 HNO 3 (aq) 206.57 110.5 146 C 6 H 6 (l) 49.0 124.5 172.8 I (aq) 55.94 51.67 109.4 Ca(OH) 2 (s) 986.09 898.56 83.39 Na 2 CO 3 (s) 1130.9 1048.1 139 Ca 2+ (aq) 542.96 533.04 55.2 NaCl (s) 411.1 384.0 72.12 CaCO 3 (s) 1206.9 1128.8 92.9 NaHCO 3 (s) 947.7 851.9 102 CaO (s) 635.1 603.5 38.2 NH 3 (g) 45.9 16 193 CH 3 COOH (aq) 487.0 392 160 N 2 H 4 (l) 50.4 149.2 121.2 CH 3 OH (l) 238.6 166.2 127 NH 4 Cl (s) 315.39 203.89 94.56 CH 4 (g) 74.87 50.81 186.1 NH + 4 (aq) 132.80 79.5 112.8 Cl 2 (g)?????????? 222.96 OH (aq) 229.94 157.30 10.54 Cl (aq) 167.46 131.17 55.10 P 4 O 10 (s) 2940.1 2698 229 Cl 2 O (g) 80.3 97.9 266.1 Pb 2+ (aq) 1.6 24.3 21 ClO 2 (g) 102 120 256.7 PbCl 2 (s) 359 314 136 CO (g) 110.5 137.2 197.5 PbSO 4 (s) 918.4 811.2 147.28 CO 2 (g) 393.5 394.4 213.7 SO 2 4 (aq) 907.5 741.99 17.15 CO 2 3 (aq) 676.3 528.1 53.1 Sr 2+ (aq) 545.5 557.3 39.33 CS 2 (g) 115.3 65.1 237.8 SrSO 4 (s) 1444.74 1334.28 121.75 CS 2 (l) 87.9 63.6 151.0 SrCl 2 (s) 828.4 781.15 117.5 Cu 2+ (aq) 64.39 64.98 99.6 SrCO 3 (s) 1218.38 1137.6 97.07