OFFICE HOURS FOR FINALS WEEK Monday May 18 1:00 pm - 4:45 pm SM 206. TEST 1 REVIEW 1. Write the K c and K p expressions for the following reactions. (a) 2KClO 3 (s) 2KCl (s) + 3O 2 (g) (b) 2NO 2 (g) + 7H 2 (g) 2NH 3 (g) + 4H 2 O (l) (c) F 2 (g) + H 2 O (g) 2HF (g) + ½O 2 (g) 2. The equilibrium constants for the following reactions are: NO (g) + ½O 2 (g) NO 2 (g) K p = 1.8 x 10 3 N 2 O 5 (g) 2NO 2 (g) + ½O 2 (g) K p = 5.3 x 10-4 Find the equilibrium constants for each of the following reactions. (a) NO 2 (g) NO (g) + ½O 2 (g) (b) 2N 2 O 5 (g) 4NO 2 (g) + O 2 (g) (c) NO (g) + NO 2 (g) + O 2 (g) N 2 O 5 (g) 3. K p is 16.0 at 298 K for the reaction: 2HBr (g) H 2 (g) + Br 2 (g) The tank is initially charged with 0.200 atm HBr, 0.500 atm H 2, and 0.500 atm Br 2 at 298 K. (a) Is the forward or reverse reaction spontaneous? (b) Calculate the pressure of HBr once equilibrium has been established. 4. The K p for the following reaction is to be determined: 2A 2 B (g) 2A 2 (g) + B 2 (g) A tank is charged with 1.00 atm of A 2 B. Complete an ICE table and calculate x for each of the following senarios. (a) the total pressure at equilibrium is found to be 1.30 atm (b) A 2 B is found to be 40.% dissociated. (c) the equilibrium pressure of A 2 B is found to be 0.80 atm.
5. Dibromine monoxide decomposes upon heating to gaseous bromine and gaseous oxygen by the following reaction: 2Br 2 O (g) 2Br 2 (g) + O 2 (g) 3.06 grams of dibromine monoxide are placed in a 125 ml flask at 20ºC. (a) Calculate the pressure of the dibromine monoxide before any decomposition occurs. (b) The flask is warmed to 65ºC, the initial pressure of the Br 2 O adjusted to 3.35 atm, and at equilibrium the total pressure is found to be 4.37 atm. Calculate K p for this reaction at 65ºC. (c) The flask is warmed to 85ºC, the initial pressure of the Br 2 O adjusted to 3.35 atm, and at equilibrium the Br 2 O is found to be 77.0% decomposed. Calculate K p for this reaction at 85ºC. (d) The flask is warmed to 105ºC, the initial pressure of the Br 2 O adjusted to 3.35 atm, and at equilibrium the partial pressure of O 2 gas is 1.45 atm. Calculate K p for this reaction at 105ºC. (e) Based upon the calculated equilibirium constants, is the reaction exothermic or endothermic? 6. Nitrogen reacts with oxygen to produce nitrogen monoxide by the following reaction: N 2 (g) + O 2 (g) 2NO (g) The K c for this reaction at 150ºC is 2.4 x 10 1. (a) A 250. ml flask is initially charged with 3.12 grams of nitrogen monoxide. Calculate the concentration of the nitrogen monoxide, in moles per liter, before any reaction occurs. (b) The container is heated to 150ºC. Calculate the equilibrium concentration of nitrogen monoxide in the flask. (c) Calculate the number of moles of nitrogen gas that must be added to the flask at 150ºC to increase the equilibrium concentration of nitrogen monoxide to 0.350 moles per liter. 7. Sodium bicarbonate decomposes upon heating according to the equation 2NaHCO 3 (s) Na 2 CO 3 (s) + H 2 O (g) + CO 2 (g) (a) A sample of 100. grams of solid sodium bicarbonate was placed in an evaculated 5.00 L container and heated to 159ºC. Some of the original solid remained, and the total pressure in the container was 7.76 atm when equilibrium was reached. Write the equilibrium expression for the equilibrium constant, K p, and calculate its numerical value. (b) Calculate the number of moles of water vapor present at equilibrium. (c) Calculate the number of grams of the original solid that remain in the container at equilibrium. (d) If 110. grams of solid sodium bicarbonate had been placed in the 5.00 L container and heated to 159ºC, what would have been the total pressure at equilibrium? Explain.
8. The following reaction is endothermic: 2ClO (l) Cl 2 (g) + O 2 (g) An equilibrium is established with all 3 species present. For each of the following disturbances, tell (1) which direction the equilibrium would shift (2) the effect on the new equilibrium pressure of Cl 2 (3) the effect on the new equilibrium pressure of O 2 (4) the effect on the new equilibrium moles of ClO (5) the effect on the numerical value of the equilibrium constant (a) Addition of chlorine gas at constant volume (b) Addition of dichlorine monoxide liquid at constant volume (c) Removal of oxygen gas at constant volume (d) A decrease in the volume of the reaction container (e) An increase in temperature (f) Adding argon gas at constant volume (g) The addition of a catalyst 9. Identify each as a Bronsted acid or Bronsted base. 2- (a) HClO (b) SO 4 10. Calculate the ph of each of the following solutions. (a) 0.020 M hydrochloric acid (b) 0.020 M sodium hydroxide (c) NH 4 + (d) HCO 3-11. Write the acid ionization equation for each, and its acid ionization constant expression (a) hydrofluoric acid (b) chlorous acid 12. Write the base dissociation equation for each, and its base dissociation constant expression (a) ammonia (b) cyanide ion 13. A 0.150 M nitrous acid solution is prepared. (a) At 35ºC the ph of the solution is 2.05. Calculate the K a at 35ºC. (b) At 45ºC the solution is 7.45% ionized. Calculate the K a at 45ºC. 14. Using data from the text book, calculate the ph and percent ionization of each of the following solutions. (a) 0.020 M hypochlorous acid (b) 0.020 M ammonia
15. A solution is 0.10 M in ascorbic acid, H 2 C 6 H 6 O 6. (a) Using data from the text book, what are the concentrations of H +, HC 6 H 6 O 6 -, C 6 H 6 O 6 2-, and H 2 C 6 H 6 O 6 in the solution? (b) What is the ph of the solution? 16. Give the conjugate base of each of the following acids. (a) hydrofluoric acid (b) carbonic acid (c) ammonium ion (d) benzoic aicd, C 6 H 5 COOH 17. Give the conjugate acid of each of the following bases. (a) ammonia (b) nitrite ion (c) sulfate ion (d) methylamine, CH 3 NH 2 18. Predict whether the following salt solutions will be acidic, basic, or neutral. (a) aqueous potassium fluoride (b) aqueous ammonium chloride (c) aqueous potassium chloride 19. Using data from the text book, calculate the ph of the following salt solutions. (a) 0.25 M potassium fluoride (b) 0.25 M ammonium chloride (c) 0.25 M sodium phenolate, NaOC 6 H 5
TEST 2 REVIEW 20. Which of the following will produce a buffer solution? (a) Mixing 50 ml of 0.20 M sodium acetate with 25 ml of 0.20 M acetic acid (b) Mixing 50 ml of 0.20 M acetic acid with 25 ml of 0.20 M sodium acetate (c) Mixing 50 ml of 0.20 M sodium acetate with 25 ml of 0.20 M hydrochloric acid (d) Mixing 50 ml of 0.20 M hydrochloric acid with 25 ml of 0.20 M sodium acetate (e) Mixing 50 ml of 0.20 M sodium acetate with 25 ml of 0.20 M sodium hydroxide (f) Mixing 50 ml of 0.20 M sodium hydroxide with 25 ml of 0.20 M sodium acetate (g) Mixing 50 ml of 0.20 M acetic acid with 25 ml of 0.20 M hydrochloric acid (h) Mixing 50 ml of 0.20 M hydrochloric acid with 25 ml of 0.20 M acetic acid (i) Mixing 50 ml of 0.20 M acetic acid with 25 ml of 0.20 M sodium hydroxide (j) Mixing 50 ml of 0.20 M sodium hydroxide with 25 ml of 0.20 M acetic acid (k) Mixing 50 ml of 0.20 M hydrochloric acid with 25 ml of 0.20 M sodium hydroxide (l) Mixing 50 ml of 0.20 M sodium hydroxide with 25 ml of 0.20 M hydrochloric acid 21. Using data from the text book, calculate the ph of each of the following solutions. (a) A solution 0.10 M in hydrocyanic acid (b) A solution 0.10 M in sodium cyanide (c) A solution 0.10 M in hydrocyanic acid and 0.10 M in sodium cyanide 22. Calculate the molar ratio of conjugate base to acid in a solution that has a ph of 9.50 and contains hydrocyanic acid and sodium cyanide. 23. Using the given data: Acid : HClO 2 HF HC 4 H 7 O 2 HCN HIO K a : 1.1 x 10-2 7.2 x 10-4 1.5 x 10-5 6.2 x 10-10 2.3 x 10-11 identify the best acid/conjugate base pair to prepare each of the following: (a) a buffer solution with a ph = 4.5 (b) a buffer with a ph = 10.5 24. A buffer solution is 0.30 M in nitrous acid and 0.30 M in lithium nitrite. Using data from the text book, calculate the ph of the solution. (a) Calculate the ph if 0.010 moles of sodium hydroxide are added to 100. ml of the buffer. (b) Calculate the ph 0.010 moles of hydrochloric acid are added to 100. ml of the buffer. (c) Calculate the ph if 20.0 ml of 0.18 M sodium hydroxide are added to 100. ml of the buffer. (d) Calculate the ph if 20.0 ml of 0.18 M hydrochloric acid are added to 100. ml of the buffer. (e) Calculate the ph if 20.0 ml of 1.8 M sodium hydroxide are added to 100. ml of the buffer. (f) Calculate the ph if 20.0 ml of 1.8 M hydrochloric acid are added to 100. ml of the buffer.
25. The acid ionization constant for propanoic acid, C 2 H 5 COOH, is 1.3 x 10-5. (a) Calculate the hydrogen ion concentration in a 0.20 M solution of propanoic acid. (b) Calculate the percentage of propanoic acid molecules that are ionized in the solution. (c) Calculate the ratio of the concentration of propanoate ion to that of propanoic acid in a buffer solution with a ph of 5.20. 26. Sodium benzoate, C 6 H 5 COONa, is a salt of the weak acid benzoic acid, C 6 H 5 COOH. A 0.10 M solution of sodium benzoate has a ph of 8.60 at room temperature. (a) Calculate the [OH - ] in the sodium benzoate solution. (b) Calculate the value for the equilibrium constant for the reaction C 6 H 5 COO - (aq) + H 2 O (l) C 6 H 5 COOH (aq) + OH - (aq) (c) Calculate the value of K a, the acid ionization constant, for benzoic acid. (d) A saturated solution of benzoic acid is prepared by adding excess solid benzoic acid to pure water at room temperature. If the saturated solution has a ph of 2.88, calculate the molar solubility of benzoic acid at room temperature. 27. A 20.0 ml sample of a weak monoprotic acid solution is titrated with a 0.150 M sodium hydroxide solution, and the titration curve for the reaction is shown below. (a) Calculate the molarity of the weak monoprotic acid solution. (b) Calculate the acid ionization constant, K a, for the weak monoprotic acid. 28. Write the dissolving reaction for each solid, and its solubilty product constant expression (a) calcium chloride (b) silver phosphate 29. The molar solubility of gold (III) fluoride is 1.8 x 10-3 M. Calculate the solubility product constant, K sp, for gold (III) fluoride. 30. The solubility prodict constant for bismuth (III) sulfide is 1.6 x 10-72. Calculate the molar solubility of bismuth (III) sulfide.
31. Methylamine, CH 3 NH 2, is a weak base that ionizes in solution as shown by the following equation: CH 3 NH 2 (aq) + H 2 O (l) CH 3 NH 3 + (aq) + OH - (aq) At 25ºC the percent ionization in a 0.160 M solution of methylamine is 4.7%. Calculate [OH - ], [CH 3 NH 3 + ], [CH 3 NH 2 ], and [H 3 O + ], and the ph of the solution. (a) Calculate the value for K b, the base ionization constant, for methylamine at 25ºC. (b) If 0.050 moles of lanthanum (III) nitrate are added to 1.00 liter of a solution containing 0.20 moles of CH 3 NH 2 and 0.20 moles of its salt, CH 3 NH 3 Cl at 25ºC, and the solution is stirred until equilibrium is attained, will any lanthanum (III) hydroxide precipitate? The solubility product constant for lanthanum (III) hydroxide, K sp, is 1 x 10-19. 32. The solubility of iron (II) hydroxide is 1.43 x 10-3 grams per liter at 25ºC. (a) Calculate the molar solubility of iron (II) hydroxide at 25ºC. (b) Calculate the value for the solubility product constant, K sp, of iron (II) hydroxide at 25ºC. (c) Calculate the ph of a saturated iron (II) hydroxide solution at 25ºC. (d) 50.0 ml of a 3.00 x 10-3 M iron (II) sulfate solution is added to 50.0 ml of a 4.00 x 10-6 M sodium hydroxide solution. Does a precipitate of Fe(OH) 2 form? 33. Write equations for each of the following nuclear processes. (a) beta positive decay by 52 25Mn (b) beta minus decay by 131 52Te (c) alpha decay by 212 84Po (d) electron capture by 92 41Nb 34. Predict the expected type of decay for the following radioisotoes. (a) 11 C (b) 14 C (c) 131 Cs (d) 135 Cs 35. If 0.747 g of 17 F decays by β + emission to 0.032 g in 5.00 minutes, what is the half-life of 17 F? 36. The half-live of 52 Mn is 5.91 days. If a sample of 52 Mn is allowed to decay for 1.00 week, calculate (a) the percentage of the 52 Mn remaining after the 1.00 week (b) the percentage of the 52 Mn that decayed away after the 1.00 week 37. The half-live of 232 Th is 1.39 x 10 10 years. If a sample of a present day ore contains 3.45 g of 232 Th, what mass of 232 Th did it contain 4.5 x 10 9 years ago? 38. Radioactive tritium, 3 H, has a half-life of 12.26 years. How long will it take for the radioactivity of a tritium sample to fall to 10.0% of its original intensity?
39. Calculate the binding energy per nucleon of 27 Al if the mass of an 27 Al atom is 26.981535 u. 40. Explain each of the following in terms of nuclear models. (a) The mass of an atom of 4 He is less than the sum of the masses of 2 protons, 2 neutrons, and 2 electrons. (b) Products from nuclear fission of uranium, such as 90 Sr and 137 Ce are highly radioactive and decay by beta minus emission. (c) Nuclear fusion requires large amounts of energy to get started, whereas nuclear fission can occure spontaneously, although both processes release energy. TEST 3 REVIEW 41. In each of the following pairs, tell which has the higher entropy. (a) H 2 O (l) or H 2 O (g) (b) NaCl (s) or NaCl (aq) (c) Cu (s) or Au (s) (d) N 2 (g) or CO (g) 42. Predict the sign of the entropy change in each of the following reactions. (a) Mg (s) + 2HCl (aq) MgCl 2 (aq) + H 2 (g) (b) 4PCl 5 (s) P 4 (s) + 10Cl 2 (g) (c) CaO (s) + CO 2 (g) CaCO 3 (s) (d) 2NO (g) N 2 (g) + O 2 (g) (exothermic) (endothermic) (exothermic) (endothermic) 43. For the reactions in question 33, predict (1) if the reaction is either definitely spontaneous, definitely nonspontaneous, or possibly spontaneous, and (2) if an increase in temperature will favor spontaneity or not. 44. For the reaction producing glucose: 6CO 2 (g) + 6H 2 O (l) C 6 H 12 O 6 (s) + 6O 2 (g) use data from the appendix to answer the following. (a) Calculate ΔHº (b) Calculate ΔSº (c) Calculate ΔGº (d) Calculate ΔGº at 298 K using ΔGº = ΔHº - T ΔSº (e) Is the reaction spontaneous under standard conditions? (f) Do the enthalpy change and the entropy change work for or against spontaneity? (g) Which factor predominates?
45. For the reaction: NO (g) + O 3 (g) NO 2 (g) + O 2 (g) (a) Calculate the standard free energy change using data from the appendix (b) Calculate the free energy change for the reaction at 298 K when p NO = 1.00 x10-6 atm, p O3 = 2.00 x10-6 atm, p NO2 = 1.00 x10-7 atm, p O2 = 1.00 x10-3 atm 46. For the reaction: HCl (g) + NH 3 (g) NH 4 Cl (s) (a) Calculate the standard free energy change using data from the appendix (b) From the standard free energy change, calculate the K eq of the reaction at 298 K. 47. When 1.000 g of propane gas is burned at 25ºC and 1.00 atm pressure, liquid water and carbon dioxide gas are formed, with the evolution of 50.33 kj of heat energy. The following thermodynamic data is given. ΔHº f (kj/mol) Sº (J/molK) CO 2 (g) -394 +214 H 2 O (l) -286 +70. O 2 (g) 0 +205 C 3 H 8 (g)? +270. (a) Write the balance equation for the combustion reaction. (b) Calculate the enthalpy of combustion of propane, in kj/mol. (c) Calculate the standard enthalpy of formation for propane, ΔHº f, in kj/mol. (d) Calculate the entropy change, ΔSº for the combustion reaction, and account for the sign of ΔSº. (e) Calculate the free energy change, ΔGº for the combustion reaction at 25ºC. 48. ClF 3 can be prepared by the following reaction. Cl 2 (g) + 3F 2 (g) 2ClF 3 (g) For ClF 3, the standard enthalpy change of formation, ΔHº f, is -163 kj/mol and the standard free energy change of formation, ΔGº f, is -123 kj/mol. (a) Calculate the value of the equilibrium constant for the reaction at 298 K. (b) Calculate the standard entropy change, ΔSº, for the reaction at 298 K. (c) If ClF 3 was produced as a liquid rather than a gas, how would the sign and magnitude ΔS for the reaction be affected? Explain. (d) At 298 K the absolute entropies of Cl 2 (g) and ClF 3 (g) are 223 J/molK and 282 J/molK, respectively. Account for the larger entropy value of ClF 3 (g) relative to that of Cl 2 (g). (e) Calculate the value of the absolute entropy of F 2 (g) at 298 K.
40. Consider the cell Al (s) Al 3+ (1.0 M) Cu 2+ (1.0 M) Cu (s) (a) Using data from the text book, calculate the Ɛº for the cell. (b) Write the half reaction that takes place at the anode. (c) Write the half reaction that takes place at the cathode. (d) Write the overall spontaneous reaction for the cell. 41. Consider the cell at 25ºC: Cr (s) Cr 3+ (0.10 M) Ag + (0.20 M) Ag (s) (a) Using data from the text book, calculate the Ɛº for a standard cell made from a Cr/Cr 3+ half-cell and a Ag/Ag + half-cell. (b) Calculate the Ɛ for the cell described above. (c) Write the half reaction that takes place at the anode. (d) Write the half reaction that takes place at the cathode. (e) Write the overall spontaneous reaction for the cell. 42. Calculate the mass of iron metal that can be obtained by passing a current of 1.00 amperes through a solution of iron (III) nitrate for 3.00 hours. 43. For the reaction below, Ɛº = 0.48 V at 25ºC. M (s) + Cu 2+ (aq) M 2+ (aq) + Cu (s) (a) Determine the standard electrode potential for the reduction half-reaction M 2+ (aq) + 2e - M (s) (b) A cell is constructed in which the above reaction occurs. All substances are initially in their standard states, and equal volumes of solutions are used. The cell is then discharged. Calculate the value of the cell potential, Ɛ, when [Cu 2+ ] has dropped to 0.20 M. (c) Find the ratio [M 2+ ]/[Cu 2+ ] when the cell reaction reaches equilibrium. (d) A current of 10.5 amperes is passed through a M 2+ solution for 120. seconds, and 0.775 grams of the metal M are deposited. Identify the metal. 44. When a dilute solution of sulfuric acid is electrolyzed, oxygen gas is produced at the anode and hydrogen gas is produced at the cathode. (a) Write the balanced equations for the anode reaction. (b) Write the balanced equation for the cathode reaction. (c) Write the balanced equation for the overall reaction that occur in this cell. (d) Calculate the coulombs of charge passed through the cell in 100. Minutes at 10.0 amperes. (e) Calculate the number of moles of oxygen produced by the cell when it is operated for 100. minutes at 10.0 amperes. (f) The standard enthalpy of formation of H 2 O (g) is -242 kj/mol. Calculate the amount of heat released by the complete combustion, at 298 K and 1.00 atm, of the hydrogen produced by the cell operated as in (d).
TEST 4 REVIEW 45. Identify each as a Lewis acid or a Lewis base. (a) Br - (b) K + (c) AlCl 3 (covalent) (d) (CH 3 ) 2 SO 46. Identify the following as strong-field ligands or weak-field ligands (a) I - (b) CN - (c) OH - (d) NO 2-47. The transistion metal complex ion, [CoF 3 Cl 2 Br] 3-, has an octahedral shape. (a) Draw the structural formulas for each of the geometrical isomers. (b) Draw the structural formulas for any optical isomers. (c) Draw d-orbital splitting patterns that would account for the complex being either paramagnetic or diamagnetic 48. The transistion metal complex ion, [Ni(NH 3 ) 4 ] 2+, has an square planar geometry, is diamagnetic, and has a formation constant, K f, of 6 x 10 8. (a) Name the complex ion. (b) Draw the d-orbital splitting pattern that would explain the shape and magnetism. (c) Nickel (II) sulfide has a solubility product constant, K sp, of 3.0 x 10-21. Calculate the molar solubilty of nickel (II) sulfide in pure water. (d) Calculate the molar solubility of nickel (II) sulfide in 1.0 M ammonia. 49. SnS 2 has a solubility product constant, K sp, of 3.2 x 10-41, and the complex ion, SnCl 6 2-, has a formation constant, K f, of 5.0 x 10 48. (a) Calculate the molar solubilty of tin (IV) sulfide in pure water. (b) Calculate the molar solubility of tin (IV) sulfide in a 3.0 M hydrochloric acid solution. 50. Draw reaction profiles for each, labeling the forward E a and the ΔH. (a) an exothermic reaction (c) the exothermic reaction in (a) catalyzed (b) an endothermic reaction (d) the endothermic reaction in (b) catalyzed
50. The hydrolysis of thioacetamide is used to generate H 2 S as shown by the equation below. S O CH 3 -C-NH 2 + H 2 O H 2 S + CH 3 -C-NH 2 The rate of the reaction is given by the following rate law: Rate = k [H + ] [CH 3 -CS-NH 2 ] Consider a solution which is 0.10 M in H + and 0.10 M in CH 3 -CS-NH 2 at 25ºC. For each of the following changes, state (1) whether the rate of the reaction increases, decreases, or remains the same, and (2) whether the specific rate constant, k, increase, decrease, or remains the same. (a) Sodium acetate is added to the solution. (b) The solution is heated to 75ºC. (c) Water is added to the solution. 51. For the reaction carried out at 30ºC the following kinetics data were obtained: A + 2B 3C + D Experiment Initial Rate of Reaction (M/hr) Initial [A] o (M) Initial [B] o (M) 1 8.00 0.240 0.480 2 2.00 0.240 0.120 3 9.00 0.360 0.240 4 0.500 0.120 0.120 5 1.00 0.240 0.0600 6? 0.0140 1.35 (a) Write the rate law expression for the reaction. (b) Calculate the value of the specific rate constant, k, at 30ºC, and specify its units. (c) Calculate the value of the initial rate of this reaction at 30ºC for the initial concentrations shown in experiment 6. (d) Assume that the reaction goes to completion. Under the conditions specified for experiment 2, what would be the final molar concentration of C?
52. For the following reaction studied at 25ºC the following results were obtained: 2ClO 2 (g) + F 2 (g) 2ClO 2 F (g) Experiment Initial Rate of Increase of [ClO 2 F] (M/s) Initial [ClO 2 ] o (M) Initial [F 2 ] o (M) 1 2.4 x 10-3 0.010 0.10 2 9.6 x 10-3 0.010 0.40 3 9.6 x 10-3 0.020 0.20 (a) Write the rate law expression for the reaction. (b) Calculate the value of the specific rate constant, k, at 30ºC, and specify its units. (c) In experiment 2, what is the initial rate of decrease of [F 2 ]? (d) Which of the following reaction mechanisms is consistant with the rate law developed in (a)? (1) (2) ClO 2 + F 2 ClO 2 F 2 (fast) F 2 2F (slow) ClO 2 F 2 ClO 2 F + F (slow) 2(ClO 2 + F ClO 2 F) (fast) ClO 2 + F ClO 2 F (fast) 53. Graphical methods are frequently used to analyze and obtyain desired quantities. (a) The following data gives the partial pressure of A as a functiuon of time and were obtained at 100ºC for the gaseous reaction given. A (g) B (g) + C (g) P A (torr) 348 214 154 99 73 t (s)0600 1,200 2,400 3,600 Determine if the reaction is zero, first, or second order in A. (b) The following data gives the rate constant at various temperatures for the gas reaction given. 2HI (g) H 2 (g) + I 2 (g) T (K) 647 706 773 845 916 k (M -1 s -1 ) 2.07 x 10-3 3.47 x 10-3 5.66 x 10-3 8.80 x 10-3 1.27 x 10-2 Calculate the activation energy for the reaction.
ANSWERS 1. (a) K c = [O 2 ] 3 K p = p O2 3 (b) K c = [NH 3 ] 2 K p = p NH3 3 [NO 2 ] 2 [H 2 ] 7 p NO2 2 p H2 7 (c) K c = [HF] 2 [O 2 ] ½ K p = p HF 2 p O2 ½ [F 2 ][H 2 O] p F2 p H2O 2. (a) 5.6 x 10-4 (b) 2.8 x 10-7 (c) 3.4 x 10 6 3. (a) forward (b) 0.133 atm 4. (a) 0.30 atm (b) 0.20 atm (c) 0.10 atm 3. (a) 3.35 atm (b) 2.47 (c) 14 (d) 60. (e) endothermic 4. (a) 0.416 M (b) 0.30 M (c) 0.030 mol 5. (a) K p = p H2Op CO2 K p = 15.1 (b) 0.547 mol (c) 8 g (d) at the same temperature the K p remains the same, so starting with pure solid NaHCO 3 the equilibrium pressures of H 2 O (g) and CO 2 (g) will have to be the same, so the total pressure will be the same as well 6. (a) shift left, increase, decrease, increase, no effect (b) no effect, no effect, no effect, increase, no effect (c) shift right, increase, decrease, decrease, no effect (d) shift left, no effect, no effect, increase, no effect (e) shift right, increase, increase, decrease, increase (f) no effect, no effect, no effect, no effect, no effect, no effect, no effect (g) no effect, no effect, no effect, no effect, no effect, no effect, no effect 7. (a) acid (b) base (c) acid (d) both! 8. (a) 1.70 (b) 12.30 9. (a) HF (aq) + H 2 O (l) H 3 O + (aq) + F - (aq) K a = [H 3 O + ][F - ] [HF] (b) HClO 2 (aq) + H 2 O (l) H 3 O + (aq) + ClO 2 - (aq) K a = [H 3 O + ][ClO 2 - ] [HClO 2 ]
10. (a) NH 3 (aq) + H 2 O (l) NH 4 + (aq) + OH - (aq) K b = [NH 4 + ][OH - ] [NH 3 ] (b) CN - (aq) + H 2 O (l) HCN (aq) + OH - (aq) K b = [HCN][OH - ] 9. (a) 5.6 x 10-4 (b) 9.00 x 10-4 10. (a) 4.58, 0.13% (b) 10.77, 3.0% [CN - ] 11. (a) 2.8 x 10-3 M H +, 2.8 x 10-3 M HC 6 H 6 O 6 -, 1.6 x 10-12 M C 6 H 6 O 6 2-, 0.10 M H 2 C 6 H 6 O 6 (b) 2.56 12. (a) F - (b) HCO 3 - (c) NH 3 (d) C 6 H 5 COO - 12. (a) NH 4 + (b) HNO 2 (c) HSO 4 - (d) CH 3 NH 3 + 12. (a) basic (b) acidic (c) neutral 12. (a) 8.27 (b) 4.93 (c) 11.60 13. a, b, c, i 14. (a) 5.10 (b) 11.10 (c) 9.21 15. 2.0:1 16. (a) HC 4 H 7 O 2 and C 4 H 7 O 2 - (b) HIO and IO - 17. (a) 3.40 (b) 3.70 (c) 3.10 (d) 3.50 (e) 3.29 (f) 12.70 (g) 1.30 18. (a) 1.6 x 10-3 M (b) 0.80% (c) 2.1:1 19. (a) 4.0 x 10-6 M (b) 1.6 x 10-10 (c) 6.3 x 10-5 (d) 0.029 M 20. (a) 0.17 M (b) 1 x 10-5 21. 2.8 x 10-10 10. (a) CaCl 2 (s) Ca 2+ (aq) + 2Cl - (aq) K sp = [Ca 2+ ][Cl - ] 2 (b) Ag 3 PO 4 (s) 3Ag + 3- (aq) + PO 4 (aq) K sp = [Ag + ] 3 [PO 3-4 ] 22. 1.7 x 10-15 M 23. (a) [OH - ] = [CH 3 NH + 3 ] = 7.5 x 10-3 M, [CH 3 NH 2 ] = 0.152 M, [H 3 O + ] = 1.3 x 10-12 M, ph = 11.88 (b) 3.7 x 10-4 (c) yes, 2.5 x 10-12 > 1 x 10-19 24. (a) 1.59 x 10-5 M (b) 1.61 x 10-14 (c) 9.503 (d) no
25. (a) 52 25Mn 52 24Cr + 0 +1β + (b) 131 52Te 131 53I + 0-1β - (c) 212 84Po 4 2α + 208 82Pb (c) 92 41Nb + 0-1e - 92 40Zr 26. (a) beta positive or electron capture (b) beta minus 27. 66 s (c) beta positive or electron capture 28. (a) 44.0% (b) 56.0% 28. 4.3 g 29. 40.7 years 30. 8.332 MeV/nucleon (d) beta minus 31. (a) Some of the mass of the protons and neutrons is converted into energy to bind the nucleus together (a) 90 Sr and 137 Ce are neutron-rich radioisotopes, and decay by beta minus emission in order to convert the excess of neutrons into protons and electrons (b) Nuclear fisson is the combining of nuclei, and large amounts of energy are needed to overcome the electrostatic repulsion when the positively charged nuclei are brought close together 32. (a) H 2 O (g) (b) NaCl (aq) (c) Au (s) (d) CO (g) 33. (a) positive (b) positive (c) negative (d) negative 34. (a) definitely spontaneous, favors spontaneity (a) possibly spontaneous, favors spontaneity (b) possibly spontaneous, does not favor spontaneity (c) definitely nonspontaneous, does not favor spontaneity 35. (a) 2802 kj (b) -262 J/K (c) 2875 kj (d) 2880 kj (c) nonspontaneous (f) enthalpy against, entropy against (h) neither 36. (a) -198 kj (b) -188 kj 37. (a) -91 kj (b) 8.9 x 10 15
38. (a) C 3 H 8 (g) + 5O 2 (g) 3CO 2 (g) + 4H 2 O (l) (b) -2219 kj (c) -107 kj/mol (d) -373 J/K (e) -2108 kj 39. (a) 1.32 x 10 43 (b) -268 J/K (c) the reaction would have a greater increase in order, therefore the entropy change would still be negative but with a larger magnitude (d) ClF 3 has (1) a higher mass and (2) is a molecule with atoms of different elements, so therefor a higher complexity (e) 203 J/molK 40. (a) 2.00 V (b) Al Al 3+ + 3e - (c) Cu 2+ + 2e - Cu (d) 2Al + 3Cu 2+ 2Al 3+ + 3Cu 41. (a) 1.53 V (b) 1.51 V (c) Cr Cr 3+ + 3e - (d) Ag + + e - Ag (e) Cr + 3Ag + Cr 3+ + 3Ag 42. 2.08 g 43. (a) -0.14V (b) 0.45 V (c) 1.7 x 10 16 (d) tin 44. (a) 2H 2 O O 2 + 4H + + 4e - (b) 2e - + 2H + H 2 (c) 2H 2 O 2H 2 + O 2 (d) 6.00 x 10 4 C (e) 1.55 x 10-1 mol (f) 75.0 kj 45. (a) base (b) acid (c) acid (d) base 46. (a) weak (b) strong (c) weak (d) strong 47. (a) (b) none
48. (a) tetraamminenickel (II) (b) (c) 5.5 x 10-11 M (a) 1.3 x 10-6 M 49. (a) 2.0 x 10-14 M (b) 6.4 x 10-3 M 49. (a) (b) (c) (d) 50. (a) rate decreases, k remains the same (b) rate increases, k increases (c) rate decreases, k remains the same 51. (a) rate = k [A] 2 [B] (b) 2.89 x 10 2 hr -1 M -2 (c) 7.66 x 10-2 M/hr (d) 0.180 M 52. (a) rate = k [ClO 2 ][F 2 ] (b) 2.4 s -1 M -1 (c) 4.8 x 10-3 M/s (d) 1 53. (a) second order (b) 33,300 J