Houston Community College System Departmental Final Examination Chemistry CHEM 1412 Final

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1 Houston Community College System Departmental Final Examination Chemistry 1412 CHEM 1412 Final 1

2 PART I (2 points each) CHEM 1412 FINAL EXAM Version F-1/06A Multiple choice - scantron. Please DO NOT write or mark on this paper. Write your correct answer on 1. In the reaction, HSO HS - H 2 S + SO 4 2-, which one of the sets below constitutes a conjugate (acidbase) pair? A) HSO 4 -, HS - B) HSO 4 -, H 2 S C) H 2 S, HS - D) H 2 S, SO Which one of the species below is insoluble in water? A) ZnSO 4 B) PbCrO 4 C) AgNO 3 D) NaC 2 H 3 O 2 3. A glucose solution is prepared by dissolving 5.10 g of glucose, C 6 H 12 O 6, in g of water. What is the molality of the glucose solution? A) m B) m C) m D) m 4. What is the expected freezing point of a solution that contains 25.0g of fructose, C 6 H 12 O 6, in 250.0g of water? K f = 1.86 C m -1 A) C B) C C) C D) C 5. Which of the following reactions accompanied by an increase in entropy? A) ZnS(s) + 3/2 O 2 (g) ZnO(s) + SO 2 (g) B) CH 4 (g) + H 2 O(g) CO(g) + 3H 2 (g) C) BaO(s) + CO 2 (g) BaCO 3 (s) D) Na 2 CO 3 (s) + CO 2 (g) + H 2 O(g) 2 NaHCO 3 (s) 6. The nuclear particle which is described by the representation, 1 1 X, is called: A) alpha particle B) electron C) neutron D) proton 7. C 4 H 8, is a hydrocarbon with one double bond. How many noncyclic isomers can be drawn? A) 1 B) 2 C) 3 D) 4 2

3 8. If the OH - ion concentration in an aqueous solution at 25.0 o C is measured as 3.4 x 10-3 M, then the ph is? A) 2.47 B) 7.22 C) 8.24 D) A galvanic cell has two electrodes. Which statement below is correct? A) Reduction takes place at the anode, which is positively charged. B) Reduction takes place at the anode, which is negatively charged. C) Reduction takes place at the cathode, which is positively charged. D) Reduction takes place at the cathode, which is negatively charged. 10. If a reaction involves a single reactant is first order with a rate constant of s -1, how much time is required for 75.0% of the initial quantity of reactant to be used up? A) 16.7 seconds B) 30.8 seconds C) 23.1 seconds D) 25.3 seconds 11. For the reaction, 2XO + O 2 2 XO 2, some data obtained from measurements of the initial rate of reaction at varying concentrations is given below. The rate law is therefore: Run # [XO] [O 2 ] rate, mmol L -1 s A) rate = k[xo] 2 [O 2 ] B) rate = k[xo] [O 2 ] C) rate = k[xo] [O 2 ] 2 D) rate = k[xo] 2 [O 2 ] Which one of the following is the strongest acid? A) HClO (K a = 3.0 x 10-8 ) B) HF (K a = 6.8 x 10-4 ) C) HNO 2 (K a = 4.5 x 10-4 ) D) HCN (K a = 4.9 x ) 13. Using the standard entropy values: H 2 (g), S o = J mol -1 K -1 I 2 (s), S o = J mol -1 K -1 HI(g), S o = J mol -1 K -1 Calculate the standard entropy change, S o, for the reaction: H 2 (g) + I 2 (g) 2 HI(g) A) J B) J C) J D) J 3

4 14. Consider the following reaction at equilibrium: 2NH 3 (g) N 2 (g) + 3H 2 (g) H = kj Adding H 2 (g) to the system at equilibrium will A) decrease the concentration of NH 3 (g) at equilibrium B) remove all of the N 2 (g) C) increase the value of the equilibrium constant D) decrease the concentration of N 2 (g) at equilibrium 15. The equilibrium constant for the reaction, H 2 (g) + I 2 (g) 2 HI(g) is 54.9 at K. What is the equilibrium constant for 4 HI(g) 2 H 2 (g) + 2 I 2 (g) under the same condition? A) B) 9.11 x 10-3 C) 3.32 x 10-4 D) A M solution of an acid, HA, has a ph = What is the value of the ionization constant, Ka, for this acid? A) 5.00 x 10-2 B) 1.25 x 10-3 C) 5.56 x 10-3 D) 6.25 x What is the balanced form of the following unbalanced redox equation that takes place in an acidic medium? NO 2 - (aq) + Cr 2 O 7 2- (aq) Cr 3+ (aq) + NO 3 - (aq) A) NO 2 - (aq) + Cr 2 O 7 2- (aq) + 8H + (aq) 2Cr 3+ (aq) + NO 3 - (aq) + 4H 2 O(l) B) 3NO 2 - (aq) + Cr 2 O 7 2- (aq) 2Cr 3+ (aq) + 3NO 3 - (aq) + 4H 2 O(l) C) 3NO 2 - (aq) + Cr 2 O 7 2- (aq) + 8H + (aq) 2Cr 3+ (aq) + 3NO 3 - (aq) + 4H 2 O(l) D) 3NO 2 - (aq) + Cr 2 O 7 2- (aq) + 16H + (aq) 2Cr 3+ (aq) + 3NO 3 - (aq) + 8H 2 O(l) 18. A buffer solution is prepared by taking moles of acetic acid ( pka = 4.74) and moles of sodium acetate in sufficient water to make liters of solution. Calculate the ph. A) 4.95 B) 4.66 C) 4.86 D) Oxidation refers to electrons, reduction refers to of electrons. A) Gain; gain B) Loss; gain C) Loss; loss D) Gain; loss 4

5 ml of 0.10 M HCl (aq) was added to 50.0 ml of 0.10 M NaOH (aq) and the mixture was stirred, then tested with a ph meter. What ph should be obtained at 25.0 o C? A) 1.95 B) C) 7.00 D) What element undergoes alpha decay to form lead-208 (Pb)? A) Radon (Rn) B) Xenon (Xe) C) Krypton (Kr) D) Polonium (Po) The solubility of silver oxalate, Ag 2 C 2 O 4, in pure water is 2.06 x 10-4 moles per liter. Calculate the value of K sp for silver oxalate from this data. A) 4.24 x 10-8 B) 8.49 x 10-8 C) 1.75 x D) 3.50 x Hydrocarbons containing a carbon-carbon triple bond are called. A) alkanes B) alkenes C) alkynes D) cyclic alkanes 24. The half-life of cobalt-60 is 5.3 yr. How much of a mg sample of cobalt-60 is left after a 10.6yr period? A) mg B) mg C) mg D) mg 25. Which of the following salts has a cation that can hydrolyze in water? A) NaCl B) Ca(NO 3 ) 2 C) Ba(C 2 H 3 O 2 ) 2 D) NH 4 Cl 26. The unit of the rate constant for a second order reaction could be. A) M -1 s -1 B) M C) M s -1 D) M 2 s For the reaction: A(g) + 2B(g) 4C(g), G = 77.8 kj. If the reaction mixture consists of 2.0 atm A, 4.0 atm B, and 2.5 atm C at 298 K, calculate the G for this reaction mixture at 298 K. (R=8.314 J/molK). A) 78.3 kj B) 7.89 kj C) 7.89 kj D) kj 5

6 28. A galvanic cell is composed of these two half cells, with the standard reduction potentials shown Zn 2+ (aq) + 2e - Zn(s) volt Cd 2+ (aq) + 2e - Cd(s) volt What is the standard free energy for the cell reaction of this galvanic cell? A) -69 KJ B) +69 KJ C) -224 KJ D) +224 KJ 29. The reaction 2H 2 O 2 2H 2 O + O 2 has the following mechanism? H 2 O 2 + I H 2 O + IO H 2 O + IO H 2 + O 2 + I The intermediate(s) in the reaction is (are): A) H 2 O B) IO C) Both A & B D) I 30. Name the following compound according to IUPAC system: CH 3 CH 3 CH CH CH 2 CH 3 CH 2 CH 3 A) 2,3-dimethylhexane B) 3-ethyl-2,4-dimethylheptane C) 3-ethyl-2-methylheptane D) None of the above 31. The system, H 2 (g) + X 2 (g) 2 HX(g) has a value of 24.4 for the constant, K c. A system being tried in a 3.00 liter reactor was charged with moles of H 2, moles of X 2 and, moles of HX. The catalyst was introduced using a remote unit, and the system was allowed to come to equilibrium. Which statement below describes the situation? A) the reaction goes to the right, Q < K B) the reaction goes to the left, Q < K C) the reaction goes to the right, Q > K D) the reaction goes to the left, Q > K 32. Predict the type of decay expected for Radon (Rn) A) alpha decay B) beta decay C) electron capture D) positron emission 33. A Lewis base is defined as a substance that A) acts as a proton donor B) increases [H + ] when placed in H 2 O C) decreases [OH ] when placed in H 2 O D) acts as a electron pair donor 6

7 34. Which of the following salt solution is basic: A) NaF B) KBr C) NH 4 NO 3 D) Zn(NO 3 ) Classify the following molecule: O CH 3 - CH 2 - CH 2 - C O -CH 3 A) ester B) aldehyde C) ketone D) carboxylic acid 7

8 CHEM FINAL EXAM Version F-1/06A ANSWERS PART I (Multiple Choice) 1. C 2. B 3. D 4. C 5. B 6. D 7. D 8. D 9. C 10. B 11. A 12. B 13. D 14. D 15. C 16. D 17. C 18. A 19. B 20. B 21. D 22. D 23. C 24. A 25. D 26. A 27. A 28. A 29. C 30. D 31. A 32. A 33. D 34. A 35. A 8

Houston Community College System Departmental SAMPLE Final Exam Chemistry 1412A

Houston Community College System Departmental SAMPLE Final Exam Chemistry 1412A 1 Final Sample Exam 1412A PART I (2 points each) Multiple choice - Please DO NOT write or mark on this paper. Write your