General Chemistry II FINAL EXAMINATION

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1 General Chemistry II 141 FINAL EXAMINATIN

2 PART I ( points each) CHEM 141 (Fall 009) Version AF09 Multiple choice - scantron. Please D NT write or mark on this paper. Write your correct answer on 1. Which of the following would be most soluble or miscible in CCl 4? A. NaCl B. H C. H D. CH 4. The density of 44% by mass sulfuric acid (44g H S 4 in 56g H ) is g/ml. The molarity of the solution is: A. 11 B. 8.0 C. 6.0 D Which of the following aqueous solutions should have the highest osmotic pressure? A M Na C 3 (aq) at 98K B M K C 3 at 98 K C. 0.10M glucose at 98 K D M Na C 3 (aq) at 98K 4. Pure cyclohexane freezes at 6.54 C and its molal freezing point depression constant is 0.0 C/m. Calculate the freezing point of a solution containing 1.0 g naphthalene, C 10 H 8, dissolved in 100.0g of cyclohexane. A C B C C C D C 5. Consider the hypothetical reaction A + 3B 6C. If the rate of consumption of B is 15.0 M/s, which of the following is true? A.The rate of disappearance of A is 10.0 M/s B.The rate of formation of C is 6.0 M/s C.The rate of disappearance of A is 0.0 M/s D.The rate of formation of C is 60.0 M/s 6. Consider the following reaction: Mn 4 - (aq) + 5 Cl 3 - (aq) + 6 H + (aq) Mn + (aq) + 5 Cl 4 - (aq) + 3H (l). The EXPERIMENTALLY determined rate law for the reaction is rate = k [Mn 4 - ] [Cl 3 - ][H + ] 1/. Which of the following statements is correct? A. The overall order of the reaction is 13 B. The order of the reaction with respect to H + (aq) is 6 C. Changing the concentration of Cl 3 - does not change the rate of the reaction. D. The overall order of the reaction is Which one of the following factors does not affect the value of the rate constant? A. Adding a catalyst B. Increasing reactant concentrations C. Changing the temperature D. Changing the surface area of reactants 8. In a first order reaction, A products, the initial concentration of A is M. After 15.0 min, the concentration of A was M. Calculate the value of the rate constant. A min -1 B min -1 C. 9.6 x 10-4 min -1 D min -1

3 9. Which is the correct equilibrium expression for the following reaction? Na (s) + C (g) Na C 3 (s) + (g) A. C. c [ Na C ][ ] 3 [ Na ][ C ] [ Na ][ C ] [ Na C ][ ] K = B. K = c K C = [ Na ] [ ] C 3 [ Na ] [ C ] K c = D. 3 [ C ] [ ] 10. For which of the following reactions will K p = K c? A. PCl 5 (g) PCl 3 (l) + Cl (g) B. Na (s) + C (g) Na C 3 (s) + (g) C. CH 4 (g) C H (g) + 3H (g) D. C(s) + H (g) C(g) + H (g) 11. Consider the following reaction: C(g) + H (g) H (g) If at equilibrium, the concentrations are [C] = M, [H ] = 0.114M, [ H] = M. What is the value of the equilibrium constant, K c? A B C. 136 D x Consider the following equilibrium: NH 4 HS(s) NH 3 (g) + H S (g); K c = 8.5 x If an instantaneous mixture of NH 4 HS(s), NH 3 (g), H S (g) has [NH 3 ] = 0.166M and [H S] =0.166M, which of the following is true? A. The mixture is at equilibrium B. The reaction is not at equilibrium; more NH 4 HS(s) will form till equilibrium is reached. C. The reaction is not at equilibrium; more NH 4 HS(s) will decompose till equilibrium is reached. D. K c = Which of the following bases has the strongest conjugate acid? A. hydrazine, K b = 1.30 x 10-6 B. NH 3, K b = 1.8x10-5 C. pyridine, K b = 1.7 x 10-9 D. methylamine, K b = 4.4 x f the following four substances, which would form basic solutions? I. NH 4 Cl II. Cu(N 3 ) III. K C 3 IV. NaF A. I and II B. I and III C. I only D. III and IV 3

4 15. If X is the molar solubility of a salt, which of the following solubility product expressions is correct? A.BaS 4, K sp = 16X B. CuC 3, K sp = 9X C. Ag C 3, K sp = 4X 3 D. Ag 3 P 4, K sp = X What is the ph of a M solution of Ca(H)? A. 1.8 B C D The ph of a M weak monoprotic acid is 6.0. The K a of the acid is. A B C D Calculate the ph of a solution containing M acetic acid (K a = 1.76 X 10 5 ) and 0.17 M sodium acetate. A B C D The ion below that is not likely to undergo hydrolysis is. A. Cu + B. HP 4 C. Cl 4 D. S - 0. Which of the following pairs of species is not a conjugate acid-base pair? A. HCl and Cl - B. NH 3 and NH - C. H S 4 and S 4 - D. H and H - 1. The pk b, of a base called hydrazine is The K a of its conjugate acid, the hydrazinium ion is A x 10-6 B C..38 D x Which of the following statements is/are correct? i. The molar entropy of a perfect crystal is always zero. ii.the standard free energy of formation of liquid mercury, Hg(l), is zero iii.the standard enthalpy of formation of zone gas, 3 (g), is zero iv.the free energy change accompanying an equilibrium process is zero. A. All of them B. ii, iii, iv C. ii & iv D. i, ii & iii 3. For a certain reaction, H = kj and S = J/K. Under what conditions does this reaction become spontaneous? A. at T > 779K B. at T < 779K C. at T > 1.8 C D. at T < 1.8 C 4. Which of the following comparisons is/are INCRRECT? i. S of KN 3 (aq) > S of KN 3 (s) ii. S of N (g, 5atm) > S of N (g, 1atm) iii. S of H (l) at 50 C > S of H (l) at 40 C iv. S of F (g) at 50 C > S of Cl (g) at 50 C v. S of Br (g) > S of Br (l) A. All of them are correct B. iv alone C. i, v D. ii & iv 4

5 5. The standard reduction potentials for Cr + (aq) and Sn + (aq) are V and V, respectively. Cr + + e - Cr Sn + + e - Sn E red = -0.91V E red = -0.14V Which element, chromium or tin, should be oxidized more readily? A. Cr B. They have the same ability to be oxidized D. Neither Cr nor Sn can be oxidized C. Sn 6. In the cell shown, which reaction occurs at the cathode? Cu(s) Cu + (aq) Ag + (aq) Ag(s) A. Cu + (aq) + e - Cu(s) B. Ag(s) Ag + (aq) + e - C. Ag + (aq) + e - Ag(s) D. Cu(s) Cu + (aq) + e - 7. What is the value of G at 98K for the reaction, Pb(s) + H + (aq) Pb + (aq) + H (g)? E = 0.13 V. A. 1 kj B kj C. 5 kj D. -5 kj 8. A radioisotope decays to give an alpha particle and Pb-08. What was the parent isotope? A. Bi-08 B. Tl-08 C. Po-1 D. Hg Identify the ester, the ketone and the ether from the following structures? H 3 C H 3 C C C H 3 C H 3 C C C H 3 C (i) (ii) (iii) (iv) (v) H A. ester : i, ether : iii, ketone : iv B. ester : i, ether : ii, ketone : v C. ester : ii, ether : iii, ketone : iv D. ester : ii, ether : i, ketone : iv 30. Calculate the ph at the equivalence point for the titration of 0.0 M HCl with 0.0 M NH 3 (K b = ). A..87 B C. 5.1 D Polonium-08 is an alpha emitter with a half-life of.90 years. How many milligrams of polonium from an original sample of.00 mg will remain after 8.00 years? A mg B mg C mg D mg 3. An unstable isotope of rhenium, 191 Re undergoes beta decay. What is the other product of this reaction? A. 191 s B. 191 W C. 190 W D. 190 s 5

6 33. Calculate G for the reaction 3N (g)+h (l) HN 3 (l)+n(g). A. 8.7 kj/mol B. 19 kj/mol C kj/mol D. -19 kj/mol 34. What is the relationship between the following compounds? H C = C Cl H C = C Cl A. Geometrical isomers B. Structural isomers C. Constitutional isomers D. Identical 35. The systematic name for the compound represented below is: CH - - CH - CH - CH - CH - CH -CH - A. 4,5-diethylheptane B. 3-ethyl-4-propylhexane C. 3,4-diethylheptane D. -ethyl-4-propylhexane 6

7 PART II (5 points each) Name Show all work - Please write your complete work in space provided. Partial credit will be given. 1. A solution is prepared by dissolving 6.00 g of a nonelectrolyte in enough water to make 1.0 L of solution. The osmotic pressure of the solution is 570 torr at 5.0 C. What is the molecular weight of the solute?. At 35 o C and 70 o C the first order rate constants of a reaction are.50 x 10-5 and 3.6 x 10-3 s -1 respectively. What is the activation Energy (E a ) (kj/mole)? (R = J/mole K). 3. A mixture of.0 mol of C(g) and.0 mol of H (g) was allowed to come to equilibrium in a l L flask at a high temperature. If K c = 4.0, what is the molar concentration of H (g) in the equilibrium mixture? C(g) + H (g) C (g) + H (g) 7

8 4. The Ka for benzoic acid is 6.3x10-5. What is the ph in a M solution of potassium benzoate, KC 6 H 5 C? 5. A solution of CdS 4 is electrolyzed between inert electrodes. How many hours must a current of 1.75 A flow to deposit 11.8 g of cadmium? 6. Draw the structure of the following compounds. You may use skeletal structures for rings (as polygons); otherwise be sure to show all atoms. a),,4-trimethylpentane b) 1-ethyl-1-propylcyclobutane c) trans-5-methyl--heptene d) -methyl-3-hexyne (show trans structure clearly) e) 1,4-dibromobenzene 8

9 CHEM 141 Formulas and Constants mass of proton = amu mass of neutron = amu c = 3.00 X 10 8 m/s F = C/(mol of e - ) = J/(V mol of e - ) K = o C R = (L atm)/(mol K) = J/(mol K) 1 g = 6.0 X 10 3 amu 1 atm = 760 mm Hg S g = kp g P A = X A P A o T f = K f m T b = K b m π = MRT PV = nrt ln[a] t = -kt + ln[a] o t 1/ = / k 1/[A] t = kt + 1/[A] o t 1/ = 1 / (k[a] o ) k = Ae -Ea/RT ln(k 1 /k ) = E a /R (1/T - 1/T 1 ) [H + ][H - ] = 1.0 X ph + ph = 14 K a K b = K w = 1.0 X ph = pk a + log([base]/[acid]) G o = H o - T S o G o = -RT ln K eq G = G o + RT lnq G o = -n F E o E = E o - (0.059/n) log Q E = mc Coulombs = Amps X seconds Soluble Compounds Important Exceptions Compounds containing N 3 none Compounds containing C H 3 none Compounds containing Cl Salts of Ag +, Hg +, Pb + Compounds containing Br Salts of Ag +, Hg +, Pb + Compounds containing I Salts of Ag +, Hg +, Pb + Compounds containing S 4 Salts of Ca +, Sr +, Ba +, Hg +, Pb + Insoluble compounds Important Exceptions Compounds containing S Compounds containing C 3 3 Compounds containing P 4 Compounds containing H Salts of ammonium, alkali metal cations and Ca +, Sr +, Ba + Salts of ammonium, alkali metal cations Salts of ammonium, alkali metal cations Salts of ammonium, alkali metal cations and Ca +, Sr +, Ba + 9

10 Key Part I 1. D. C 3. D 4. C 5. A 6. D 7. B 8. B 9. D 10. A 11. C 1. D 13. C 14.D 15. C 16. A 17. A 18. A 19. C 0. C 1.D. C 3. B 4. D 5. A 6. C 7. D 8. C 9. D 30. C 31. B 3. A 33. A 34. A 35. C 10

Houston Community College System Departmental Final Examination Chemistry CHEM 1412 Final

Houston Community College System Departmental Final Examination Chemistry 1412 CHEM 1412 Final 1 PART I (2 points each) CHEM 1412 FINAL EXAM Version F-1/06A Multiple choice - scantron. Please DO NOT write