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1. Which of the following concentration measures will change in value as the temperature of a solution changes? a) mass percent b) mole fraction c) molality d) molarity e) all of these Ans:  d 2. A solution containing 406.7 g of Mg(NO3)2 per liter has a density of 1.114 g/mL. The molarity of the solution is: a) 2.742 M b) 2.461 M c) 8.226 M d) 3.054 M e) none of these Ans:  a 3. What is the molality of a solution of 33.0 g of propanol (CH3CH2CH2OH) in 152 mL water, if the density of water is 1.00 g/mL? a) 3.61 m b) 0.00361 m c) 0.277 m d) 0.549 m e) 5.49 m Ans:  a 4. Which of the following chemical or physical changes is an endothermic process? a) the evaporation of water b) the combustion of gasoline c) the mixing of sulfuric acid and water d) the freezing of water e) none of these Ans:  a 5. Which of the following correctly states the relationship between temperature and the solubility of a substance in water? a) The solubility of a substance in water increases as the temperature rises, especially for gases. b) The solubility of a substance in water decreases as the temperature rises, especially for ionic solids. c) The solubility of a substance in water with temperature cannot be accurately predicted, especially for ionic solids. d) The solubility of a substance in water decreases as the temperature lowers, especially for gases. e) Both A and D are correct. Ans:  c 6. Consider the reaction HNO2(aq) + H2O(l) H3O+(aq) + NO2–(aq). Which species is a conjugate base? a) HNO2(aq) b) H2O(l) c) H3O+(aq) d) NO2–(aq) e) two of these Ans:  e 7. In which of the following reactions does the H2PO4– ion act as an acid? a) H3PO4 + H2O  H3O+ + H2PO4– b) H2PO4– + H2O  H3O+ + HPO42– c) H2PO4– + OH–  H3PO4 + O2– d) The ion cannot act as an acid. e) Two of these. Ans:  b 8. Which of the following is not true for a solution at 25°C that has a hydroxide concentration of 2.5 10–6 M? a) Kw = 1  10–14 b) The solution is acidic. c) The solution is basic. d) The [H+] is 4.0  10–9 M. e) The Kw is independent of what the solution contains. Ans:  b 9. Calculate the [H+] in a solution that has a pH of 10.08. a) 3.9 M b) 10.1 M c) 1.2  10–4 M d) 8.3  10–11 M e) none of these Ans:  d 10. The pH of a solution at 25°C in which [OH–] = 3.3  10–5 M is: a) 4.48 b) 3.30 c) 9.52 d) 4.76 e) none of these Ans:  c 11. Solid calcium hydroxide is dissolved in water until the pH of the solution is 10.16. The hydroxide ion concentration [OH–] of the solution is: a) 6.9  10–11 M b) 2.9  10–4 M c) 1.4  10–4 M d) 7.2  10–5 M e) none of these Ans:  c 12. At 5°C, the ion-product constant of water, Kw, is 1.87  10–15 The pH of pure water at 5°C is: a) 7.000 b) 7.464 c) 6.784 d) 7.364 e) none of these Ans:  d 16. Consider the reaction X  Y + Z Which of the following is a possible rate law? a) Rate = k[X] b) Rate = k[Y] c) Rate = k[Y][Z] d) Rate = k[X][Y] e) Rate = k[Z] Ans:  a 17. The pKa of HOCl is 7.5. Calculate the pH of a 0.53 M solution of HOCl. a) 7.50 b) 6.50 c) 3.89 d) 10.11 e) 0.53 Ans:  c 18. 15.0 mL of 0.50 M HCl is added to a 100.-mL sample of 0.462 M HNO2 (Ka for HNO2 = 4.0 10–4). What is the equilibrium concentration of NO2– ions? a) 2.5  10–3 M b) 1.6  10–4 M c) 4.0  10–1 M d) 5.0  10–2 M e) none of these Ans:  a 19. Which of the following statements is correct? a) The internal energy of a system increases when more work is done by the system than heat was flowing into the system. b) The internal energy of a system decreases when work is done on the system and heat is flowing into the system. c) The system does work on the surroundings when an ideal gas expands against a constant external pressure. d) All statements are true. e) All statements are false. Ans:  c 20. Of energy, work, enthalpy, and heat, how many are state functions? a) 0 b) 1 c) 2 d) 3 e) 4 Ans:  c 21. How much heat is required to raise the temperature of a 4.48-g sample of iron (specific heat = 0.450 J/g°C) from 25.0°C to 79.8°C? a) 1.98 J b) 246 J c) 546 J d) 661 J e) 110 J Ans:  e 22. Consider the reaction H2(g) + O2(g)  H2O(l) H° = –286 kJ Which of the following is true? a) The reaction is exothermic. b) The reaction is endothermic. c) The enthalpy of the products is less than that of the reactants. d) Heat is absorbed by the system. e) Both A and C are true. Ans:  e 23. What is the specific heat capacity of zinc if it requires 146 J to raise the temperature of 15 grams of zinc by 25°C? a) 2.6 J/g°C b) 0.39 J/g°C c) 0.23 J/g°C d) 0.60 J/g°C e) none of these Ans:  b 24. At 25°C, the following heats of reaction are known: H (kJ/mol) 2ClF + O2  Cl2O + F2O 167.4 2ClF3 + 2O2  Cl2O + 3F2O 341.4 2F2 + O2  2F2O –43.4 At the same temperature, calculate H for the reaction: ClF + F2 → ClF3 a) –217.5 kJ/mol b) –130.2 kJ/mol c) +217.5 kJ/mol d) –108.7 kJ/mol e) none of these Ans:  d 25. The second law of thermodynamics states that: a) The entropy of a perfect crystal is zero at 0 K. b) The entropy of the universe is constant. c) The energy of the universe is increasing. d) The entropy of the universe is increasing. e) The energy of the universe is constant. Ans:  d 26. Which of the following statements is true? a) The total energy and entropy of the universe are both increasing. b) The total energy of the universe is increasing, but the entropy is constant. c) The total energy of the universe increases, while the entropy decreases. d) The total energy of the universe is constant, but the entropy is increasing. e) None of these. Ans:  d 27. If the change in entropy of the surroundings for a process at 451 K and constant pressure is -326 J/K, what is the heat flow absorbed by for the system? a) 326 kJ b) 1.38 kJ c) –147 kJ d) 125 kJ e) 147 kJ Ans:  e 28. Given that Hvap is 62.5 kJ/mol, and the boiling point is 83.4°C, 1 atm, if one mole of this substance is vaporized at 1 atm, calculate Ssurr. a) –175 J/K mol b) 175 J/K mol c) 749 J/K mol d) –749 J/K mol e) 0 Ans:  a 29. Which of the following is true? a) By spontaneous we mean that the reaction or process will always proceed to the right (as written) even if very slowly. Increasing the temperature may speed up the reaction, but it does not affect the spontaneity of the reaction. b) By spontaneous we mean that the reaction or process will always proceed to the left (as written) even if very slowly. Increasing the temperature may speed up the reaction, but it does not affect the spontaneity of the reaction. c) By spontaneous we mean that the reaction or process will always proceed to the left (as written) even if very slowly. Increasing the temperature may speed up the reaction and it generally affects the spontaneity of the reaction. d) By spontaneous we mean that the reaction or process will always proceed to the right (as written) even if very slowly. Increasing the temperature may speed up the reaction, and it generally affects the spontaneity of the reaction. e) None of the above is true. Ans:  d 30. Equilibrium is reached in chemical reactions when: a) The rates of the forward and reverse reactions become equal. b) The concentrations of reactants and products become equal. c) The temperature shows a sharp rise. d) All chemical reactions stop. e) The forward reaction stops. Ans:  a 31. For the reaction given below, 2.00 moles of A and 3.00 moles of B are placed in a 6.00-L container. At equilibrium, the concentration of A is 0.282 mol/L. What is the concentration of B at equilibrium? a) 0.282 mol/L b) 0.397 mol/L c) 0.500 mol/L d) 0.564 mol/L e) none of these Ans:  b 32. The value of the equilibrium constant, K, is dependent on: I. the temperature of the system II. the nature of the reactants and products III. the concentration of the reactants IV. the concentration of the products a) I, II b) II, III c) III, IV d) It is dependent on three of the above choices. e) It is not dependent on any of the above choices. Ans:  a 33. Which expression correctly describes the equilibrium constant for the following reaction? 4NH3(g) + 5O2(g) 4NO(g) + 6H2O(g) a) K = ( 4[NH3] + 5[O2] ) / ( 4[NO] + 6[H2O] ) b) K = ( 4[NO] + 6[H2O] ) / (4[NH3] + 5[O2] ) c) K = ( [NO][H2O] ) / ( [NH3][O2] ) d) K = ( [NO]4[H2O]6 ) / ( [NH3]4[O2]5 ) e) K = ( [NH3]4[O2]5 ) / ( [NO]4[H2O]6 ) Ans:  d Chapter #19 Nuclear Chemistry ⦁ Balancing nuclear equations provides an excellent opportunity to review balancing by atoms, charge, and the meanings of the mass number and atomic number in element notation. ⦁ In a nuclear decay the product is a different element. Therefore we cannot balance the equation by balancing the atoms. ⦁ In forming ions the number of electrons changes but the number of proton (and therefore the type of atom) remains the same. In nuclear equations if the number of protons is changed the atoms identity is also changed. ⦁ Alchemists attempted to convert base metals (such as lead) to precious metals (such as gold) by chemical means. We now know that this can be accomplished only by nuclear reactions, which is not practical. ⦁ Nuclear transformations are balanced in the same way as nuclear decay reactions. ⦁ Radioisotopes are found in many household devices. Some examples are starters for fluorescent lamps and appliances (promethium-147, krypton-85, and thorium-232); antistatic devices (polonium-210); smoke detectors (americium-241). ⦁ C