1B HW 5As

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SCI 321
SCI 313
TEST 1 REVIEW
1. Write the Kc and Kp expressions for the following reactions.
(a) 2KClO3 (s) ⇆ 2KCl (s) + 3O2 (g)
(b) 2NO2 (g) + 7H2 (g) ⇆ 2NH3 (g) + 4H2O (l)
(c) F2 (g) + H2O (g) ⇆ 2HF (g) + ½O2 (g)
2. The equilibrium constants for the following reactions are:
NO (g) + ½O2 (g) ⇆ NO2 (g)
Kp = 1.8 x 103
N2O5 (g) ⇆ 2NO2 (g) + ½O2 (g)
Kp = 5.3 x 10-4
Find the equilibrium constants for each of the following reactions.
(a) NO2 (g) ⇆ NO (g) + ½O2 (g)
(b) 2N2O5 (g) ⇆ 4NO2 (g) + O2 (g)
(c) NO (g) + NO2 (g) + O2 (g) ⇆ N2O5 (g)
3. Kp is 16.0 at 298 K for the reaction:
2HBr (g) ⇆ H2 (g) + Br2 (g)
The tank is initially charged with 0.200 atm HBr, 0.500 atm H2, and 0.500 atm Br2 at 298 K.
(a) Is the forward or reverse reaction spontaneous?
(b) Calculate the pressure of HBr once equilibrium has been established.
4. The Kp for the following reaction is to be determined:
2A2B (g) ⇆ 2A2 (g) + B2 (g)
A tank is charged with 1.00 atm of A2B. 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) A2B is found to be 40.% dissociated.
(c) the equilibrium pressure of A2B is found to be 0.80 atm.
(continued on next page)
5. Dibromine monoxide decomposes upon heating to gaseous bromine and gaseous oxygen by the
following reaction:
2Br2O (g) ⇆ 2Br2 (g) + O2 (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 Br2O adjusted to 3.35 atm, and at
equilibrium the total pressure is found to be 4.37 atm. Calculate Kp for this reaction at 65ºC.
(c) The flask is warmed to 85ºC, the initial pressure of the Br2O adjusted to 3.35 atm, and at
equilibrium the Br2O is found to be 77.0% decomposed. Calculate Kp for this reaction at 85ºC.
(d) The flask is warmed to 105ºC, the initial pressure of the Br2O adjusted to 3.35 atm, and at
equilibrium the partial pressure of O2 gas is 1.45 atm. Calculate Kp 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:
N2 (g) + O2 (g) ⇆ 2NO (g)
The Kc for this reaction at 150ºC is 2.4 x 101.
(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
2NaHCO3 (s) ⇆ Na2CO3 (s) + H2O (g) + CO2 (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, Kp, 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.
(continued on next page)
8. The following reaction is endothermic:
2ClO (l) ⇆ Cl2 (g) + O2 (g)
An equilibrium is established with all 3 species present. For each of the following disturbances, tell
(1)
(2)
(3)
(4)
(5)
which direction the equilibrium would shift
the effect on the new equilibrium pressure of Cl2
the effect on the new equilibrium pressure of O2
the effect on the new equilibrium moles of ClO
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.
(a) HClO
(b) SO42-
(c) NH4+
(d) HCO3-
10. Calculate the pH of each of the following solutions.
(a) 0.020 M hydrochloric acid
(b) 0.020 M sodium hydroxide
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 Ka at 35ºC.
(b) At 45ºC the solution is 7.45% ionized. Calculate the Ka 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
(continued on next page)
15. A solution is 0.10 M in ascorbic acid, H2C6H6O6.
(a) Using data from the text book, what are the concentrations of H+, HC6H6O6-, C6H6O62-, and
H2C6H6O6 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, C6H5COOH
17. Give the conjugate acid of each of the following bases.
(a) ammonia
(b) nitrite ion
(c) sulfate ion
(d) methylamine, CH3NH2
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, NaOC6H5
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
Ka :
:
HClO2
1.1 x 10-2
HF
7.2 x 10-4
HC4H7O2
1.5 x 10-5
HCN
6.2 x 10-10
HIO
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 of 100. mL of the buffer.
(b) Calculate the pH if 0.010 moles of sodium hydroxide are added to 100. mL of the buffer.
(c) Calculate the pH 0.010 moles of hydrochloric acid are added to 100. mL of the buffer.
(d) Calculate the pH if 20.0 mL of 0.18 M sodium hydroxide are added to 100. mL of the buffer.
(e) Calculate the pH if 20.0 mL of 0.18 M hydrochloric acid are added to 100. mL of the buffer.
(f) Calculate the pH if 20.0 mL of 1.8 M sodium hydroxide are added to 100. mL of the buffer.
(g) Calculate the pH if 20.0 mL of 1.8 M hydrochloric acid are added to 100. mL of the buffer.
(continued on next page)
25. The acid ionization constant for propanoic acid, C2H5COOH, 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, C6H5COONa, is a salt of the weak acid benzoic acid, C6H5COOH. 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
C6H5COO- (aq) + H2O (l) ⇆ C6H5COOH (aq) + OH- (aq)
(c) Calculate the value of Ka, 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, use the Ka value to 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, Ka, 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,
Ksp, 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.
(continued on next page)
31. Methylamine, CH3NH2, is a weak base that ionizes in solution as shown by the following equation:
CH3NH2 (aq) + H2O (l) ⇆ CH3NH3+ (aq) + OH- (aq)
At 25ºC the percent ionization in a 0.160 M solution of methylamine is 4.7%.
(a) Calculate [OH-], [CH3NH3+], [CH3NH2], and [H3O+], and the pH of the solution.
(b) Calculate the value for Kb, the base ionization constant, for methylamine at 25ºC.
(c) If 0.050 moles of lanthanum (III) nitrate are added to 1.00 liter of a solution containing 0.20
moles of CH3NH2 and 0.20 moles of its salt, CH3NH3Cl 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, Ksp, 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, Ksp, 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 5225Mn
(b) beta minus decay by 13152Te
(c) alpha decay by 21284Po
(d) electron capture by 9241Nb
34. Predict the expected type of decay for the following radioisotoes.
(a)
11
C
(b)
14
C
(a)
131
Cs
(b)
135
Cs
35. If 0.747 g of 17F decays by β+ emission to 0.032 g in 5.00 minutes, what is the half-life of 17F?
36. The half-live of 52Mn is 5.91 days. If a sample of 52Mn is allowed to decay for 1.00 week, calculate
(a) the percentage of the 52Mn remaining after the 1.00 week
(b) the percentage of the 52Mn that decayed away after the 1.00 week
37. The half-live of 232Th is 1.39 x 1010 years. If a sample of a present day ore contains 3.45 g of 232Th,
what mass of 232Th did it contain 4.5 x 109 years ago?
38. Radioactive tritium, 3H, 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?
(continued on next page)
39. Calculate the binding energy per nucleon of 27Al if the mass of an 27Al atom is 26.981535 u.
40. Explain each of the following in terms of nuclear models.
(a) The mass of an atom of 4He 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 90Sr and 137Ce 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) H2O (l) or H2O (g)
(b) NaCl (s) or NaCl (aq)
(c) Cu (s) or Au (s)
(d) N2 (g) or CO (g)
42. Predict the sign of the entropy change in each of the following reactions.
(a) Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g)
(b) 4PCl5 (s) → P4 (s) + 10Cl2 (g)
(exothermic)
(endothermic)
(c) CaO (s) + CO2 (g) → CaCO3 (s)
(d) 2NO (g) → N2 (g) + O2 (g)
(exothermic)
(endothermic)
43. For the reactions in question 42, 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:
6CO2 (g) + 6H2O (l)  C6H12O6 (s) + 6O2 (g)
use data from Handout 5 on the class website 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?
(continued on next page)
45. For the reaction:
NO (g) + O3 (g) → NO2 (g) + O2 (g)
(a) Calculate the standard free energy change using data from Handout 5 on the class website
(b) Calculate the free energy change for the reaction at 298 K when pNO = 1.00 x10-6 atm,
pO3 = 2.00 x10-6 atm, pNO2 = 1.00 x10-7 atm, pO2 = 1.00 x10-3 atm
46. For the reaction:
HCl (g) + NH3 (g) ⇆ NH4Cl (s)
(a) Calculate the standard free energy change using data from Handout 5 on the class website
(b) From the standard free energy change, calculate the Keq 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.
CO2 (g)
H2O (l)
O2 (g)
C3H8 (g)
ΔHºf (kJ/mol)
Sº (J/molK)
-394
-286
0
?
+214
+70.
+205
+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, ΔHºf, 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. ClF3 can be prepared by the following reaction.
Cl2 (g) + 3F2 (g) → 2ClF3 (g)
For ClF3, the standard enthalpy change of formation, ΔHºf, is -163 kJ/mol and the standard free energy
change of formation, ΔGºf, is -123 kJ/mol.
(a) Calculate the value of the equilibrium constant for the above reaction at 298 K.
(b) Calculate the standard entropy change, ΔSº, for the above reaction at 298 K.
(c) If ClF3 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 Cl2 (g) and ClF3 (g) are 223 J/molK and 282 J/molK,
respectively. Account for the larger entropy value of ClF3 (g) relative to that of Cl2 (g).
(e) Calculate the value of the absolute entropy of F2 (g) at 298 K.
(continued on next page)
49. Consider the cell
Al (s) | Al3+ (1.0 M) || Cu2+ (1.0 M) | Cu (s)
(a) Using data from Handout 6 ont he class website, 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.
50. Consider the cell at 25ºC:
Cr (s) | Cr3+ (0.10 M) || Ag+ (0.20 M) | Ag (s)
(a) Using data from Handout 6 on the class website, calculate the Ɛº for a standard cell made from a
Cr/Cr3+ 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.
51. 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.
52. For the reaction below, Ɛº = 0.48 V at 25ºC.
M (s) + Cu2+ (aq) → M2+ (aq) + Cu (s)
(a) Determine the standard electrode potential for the reduction half-reaction M2+(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 [Cu2+] has dropped to 0.20 M.
(c) Find the ratio [M2+]/[Cu2+] when the cell reaction reaches equilibrium.
(d) A current of 10.5 amperes is passed through a M2+ solution for 120. seconds, and 0.775 grams of
the metal M are deposited. Identify the metal.
53. 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 H2O (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
54. Identify each as a Lewis acid or a Lewis base.
(a) Br-
(b) K+
(c) AlCl3 (covalent)
(d) (CH3)2SO
55. Identify the following as strong-field ligands or weak-field ligands
(a)
I-
(b) CN-
(c) OH-
(d) NO2-
56. The transistion metal complex ion, [CoF3Cl2Br]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
57. The transistion metal complex ion, [Ni(NH3)4]2+, has an square planar geometry, is diamagnetic, and
has a formation constant, Kf, of 6 x 108.
(a) Name the complex ion.
(b) Look up the d-orbital splitting pattern for a square planar ligand field, and fill in the d electrons of
the metal that would explain the magnetism.
(c) Nickel (II) sulfide has a solubility product constant, Ksp, 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.
58. SnS2 has a solubility product constant, Ksp, of 3.2 x 10-41, and the complex ion, SnCl62-, has a
formation constant, Kf, of 5.0 x 1048.
(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.
59. Draw reaction profiles for each, labeling the forward Ea and the ΔH.
(a) an exothermic reaction
(b) an endothermic reaction
(c) the exothermic reaction in (a) catalyzed
(d) the endothermic reaction in (b) catalyzed
(continued on next page)
60. The hydrolysis of thioacetamide is used to generate H2S as shown by the equation below.
S
O
║
║
CH3-C-NH2 + H2O → H2S + CH3-C-NH2
The rate of the reaction is given by the following rate law:
Rate = k [H+] [CH3-CS-NH2]
Consider a solution which is 0.10 M in H+ and 0.10 M in CH3-CS-NH2 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.
61. For the reaction carried out at 30ºC
A + 2B → 3C + D
the following kinetics data were obtained:
Experiment
Initial Rate of Reaction (M/hr)
1
2
3
4
5
6
8.00
2.00
9.00
0.500
1.00
?
Initial [A]o (M)
0.240
0.240
0.360
0.120
0.240
0.0140
Initial [B]o (M)
0.480
0.120
0.240
0.120
0.0600
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?
(continued on next page)
62. For the following reaction studied at 25ºC
2ClO2 (g) + F2 (g) → 2ClO2F (g)
the following results were obtained:
Experiment
Initial Rate of Increase of [ClO2F] (M/s)
Initial [ClO2]o (M)
-3
1
2
3
2.4 x 10
9.6 x 10-3
9.6 x 10-3
Initial [F2]o (M)
0.010
0.010
0.020
0.10
0.40
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 [F2]?
(d) Which of the following reaction mechanisms is consistant with the rate law developed in (a)?
(1) (2)
ClO2 + F2 ↔ ClO2F2
ClO2F2 → ClO2F + F
ClO2 + F → ClO2F
(fast)
(slow)
(fast)
F2 → 2F
2(ClO2 + F → ClO2F)
(slow)
(fast)
63. 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)
PA (torr)
t (s)
348
0
214
600
154
1,200
99
2,400
73
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) → H2 (g) + I2 (g)
T (K)
k (M-1s-1)
647
2.07 x 10-3
706
3.47 x 10-3
Calculate the activation energy for the reaction.
773
5.66 x 10-3
845
8.80 x 10-3
916
1.27 x 10-2
ANSWERS
1. (a) Kc = [O2]3
Kp = pO23
[NH3]2
(b) Kc =
_____________________
[NO2]2[H2]7
(c) Kc =
pNH33
Kp =
__________________________
pNO22 pH27
[HF]2[O2]½
Kp = pHF2pO2½
________________________
_____________________
[F2][H2O]
pF2 pH2O
2. (a) 5.6 x 10-4
(b) 2.8 x 10-7
(c) 3.4 x 106
3. (a) forward
(b) 0.133 atm
4. (a) 0.30 atm
(b) 0.20 atm
(c) 0.10 atm
5. (a) 3.35 atm
(b) 2.47
(c) 14
6. (a) 0.416 M
(b) 0.30 M
(c) 0.030 mol
7. (a) Kp = pH2OpCO2
Kp = 15.1
(b) 0.547 mol
(d) 60.
(e) endothermic
(c) 8 g
(d) at the same temperature the Kp remains the same, so starting with pure solid NaHCO3 the
equilibrium pressures of H2O (g) and CO2 (g) will have to be the same, so the total pressure will
be the same as well
8. (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
9. (a) acid
(b) base
10. (a) 1.70
(b) 12.30
(c) acid
11. (a) HF (aq) + H2O (l) ⇆ H3O+ (aq) + F- (aq)
(d) both!
Ka = [H3O+][F-]
_______________________
[HF]
(b) HClO2 (aq) + H2O (l) ⇆ H3O+ (aq) + ClO2- (aq)
Ka = [H3O+][ClO2-]
_______________________________
[HClO2]
(continued on next page)
12. (a) NH3 (aq) + H2O (l) ⇆ NH4+ (aq) + OH- (aq)
Kb = [NH4+][OH-]
____________________________
[NH3]
(b) CN- (aq) + H2O (l) ⇆ HCN (aq) + OH- (aq)
Kb = [HCN][OH-]
___________________________
[CN-]
13. (a) 5.6 x 10-4
(b) 9.00 x 10-4
14. (a) 4.58, 0.13%
(b) 10.77, 3.0%
15. (a) 2.8 x 10-3 M H+, 2.8 x 10-3 M HC6H6O6-, 1.6 x 10-12 M C6H6O62-, 0.10 M H2C6H6O6
(b) 2.56
16. (a) F-
(b) HCO3-
(c) NH3
(d) C6H5COO-
17. (a) NH4+
(b) HNO2
(c) HSO4-
(d) CH3NH3+
18. (a) basic
(b) acidic
(c) neutral
19. (a) 8.27
(b) 4.93
(c) 11.60
(b) 11.10
(c) 9.21
20. a, b, c, i
21. (a) 5.10
22. 2.0:1
23. (a) HC4H7O2 and C4H7O2-
(b) HIO and IO-
24. (a) 3.40
(b) 3.70
(c) 3.10
(f) 12.70
(g) 1.30
25. (a) 1.6 x 10-3 M
(b) 0.80%
(c) 2.1:1
26. (a) 4.0 x 10-6 M
(b) 1.6 x 10-10
(c) 6.3 x 10-5
27. (a) 0.17 M
(b) 1 x 10-5
(e) 3.29
28. (a) CaCl2 (s) ⇆ Ca2+ (aq) + 2Cl- (aq)
(b) Ag3PO4 (s) ⇆ 3Ag+ (aq) + PO43- (aq)
(d) 3.50
(d) 0.029 M
Ksp = [Ca2+][Cl-]2
Ksp = [Ag+]3[PO43-]
29. 2.8 x 10-10
30. 1.7 x 10-15 M
31. (a) [OH-] = [CH3NH3+] = 7.5 x 10-3 M , [CH3NH2] = 0.152 M, [H3O+] = 1.3 x 10-12 M , pH = 11.88
(b) 3.7 x 10-4
(continued on next page)
(c) yes, 2.5 x 10-12 > 1 x 10-19
32. (a) 1.59 x 10-5 M
33. (a)
52
25Mn

52
24Cr
(b)
131
52Te

131
(c)
212
84Po

4
(c)
92
41Nb
+
0
(b) 1.61 x 10-14
53I
0
+1β
+
+
0
-1β
2α
+
208
-

92
-1e
(c) 9.503
(d) no
+
-
82Pb
40Zr
34. (a) beta positive or electron capture
(b) beta minus
(c) beta positive or electron capture
(d) beta minus
35. 66 s
36. (a) 44.0%
(b) 56.0%
37. 4.3 g
38. 40.7 years
39. 8.332 MeV/nucleon
40. (a) Some of the mass of the protons and neutrons is converted into energy to bind the nucleus
together
(a)
90
Sr and 137Ce 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
41. (a) H2O (g)
(b) NaCl (aq)
(c) Au (s)
(d) CO (g)
42. (a) positive
(b) positive
(c) negative
(d) negative
43. (a) definitely spontaneous, favors spontaneity
(b) possibly spontaneous, favors spontaneity
(c) possibly spontaneous, does not favor spontaneity
(d) definitely nonspontaneous, does not favor spontaneity
44. (a) 2802 kJ
(c) nonspontaneous
(b) -262 J/K
(f) enthalpy against, entropy against
45. (a) -198 kJ
(b) -188 kJ
46. (a) -91 kJ
(b) 8.9 x 1015
(continued on next page)
(c) 2875 kJ
(d) 2880 kJ
(g) neither
47. (a) C3H8 (g) + 5O2 (g) → 3CO2 (g) + 4H2O (l)
(b) -2219 kJ
(c) -107 kJ/mol
48. (a) 1.32 x 1043
(d) -373 J/K
(e) -2108 kJ
(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) ClF3 has (1) a higher mass and (2) is a molecule with atoms of different elements, so therefor a
higher complexity
(e) 203 J/molK
49. (a) 2.00 V
(b) Al → Al3+ + 3e-
(c) Cu2+ + 2e- → Cu
(d) 2Al + 3Cu2+ → 2Al3+ + 3Cu
50. (a) 1.53 V
(b) 1.51 V
(c) Cr → Cr3+ + 3e-
(d) Ag+ + e- → Ag
(e) Cr + 3Ag+ → Cr3+ + 3Ag
51. 2.08 g
52. (a) -0.14V
(b) 0.45 V
53. (a) 2H2O → O2 + 4H+ + 4e-
(c) 1.7 x 1016
(d) tin
(b) 2e- + 2H+ → H2
(c) 2H2O → 2H2 + O2
(d) 6.00 x 104 C
(e) 1.55 x 10-1 mol
(f) 75.0 kJ
54. (a) base
(b) acid
(c) acid
(d) base
55. (a) weak
(b) strong
(c) weak
(d) strong
56. (a)
(b) none
(c)
(continued on next page)
57. (a) tetraamminenickel (II)
-11
(c) 5.5 x 10
(b)
M
-6
(d) 1.3 x 10 M
58. (a) 2.0 x 10-14 M
(b) 6.4 x 10-3 M
59. (a)
(b)
60. (a) rate decreases, k remains the same
(c)
(d)
(b) rate increases, k increases
(c) rate decreases, k remains the same
61. (a) rate = k [A]2[B]
(b) 2.89 x 102 hr-1M-2
(c) 7.66 x 10-2 M/hr
(d) 0.180 M
62. (a) rate = k [ClO2][F2]
(b) 2.4 s-1M-1
(c) 4.8 x 10-3 M/s
(d) 1
63. (a) second order
(b) 33,300 J
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