Exam of General Chemistry :ch.18-19
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MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) When the following half-reaction is balanced, the number of electrons and the type of process (oxidation or reduction) is
ClO2 ClO3-
A) 1, oxidation. B) 3, oxidation. C) 1, reduction. D) 2, oxidation. E) 2, reduction.
Answer: A
2) Which of the species in the following electrochemical reaction is oxidized?
Mg (s) + Cu2+ (aq) Mg2+ (aq) + Cu (s) A) Cu (s)
B) Cu2+ (aq) C) Mg2+ (aq) D) Mg (s)
E) not a redox reaction Answer: D
3) Which of the following nuclides would be most likely to be radioactive?
A) 13C B) 18O C) 23Na D) 28P E) 27Al
Answer: D
4) Which of the following variables are NOT needed to solve the van't Hoff equation?
A) temperature B) enthalpy C) entropy
D) equilibrium constant E) universal gas constant Answer: C
5) When the following half-reaction is balanced, the number of electrons and the type of process (oxidation or reduction) is
MnO4- (aq) Mn2+ (aq)
A) 5, oxidation. B) 1, oxidation. C) 1, reduction. D) 3, oxidation. E) 5, reduction.
Answer: E
Table 18.1 Selected Standard Electrode Potentials at 25°C
Reaction E°, V
Mg2+(aq) + 2 e- Mg(s) -2.356
Fe2+(aq) + 2 e- Fe(s) -0.440
Pb2+(aq) + 2 e- Pb(s) -0.125
2 H+ (aq) + 2 e- H2(g) 0.0
Cu2+ (aq) + 2 e- Cu(s) +0.337
I2 (s) + 2 e- 2 I-(s) +0.535
Fe3+ (aq) + 2 e- Fe2+ (aq) +0.771
Ag+ (aq) + e- Ag(s) +0.800
O2 (g) + 4 H+ (aq) + 2 e- 2 H2O +1.229
Cl2 (g) + 2 e- 2 Cl- (aq) +1.358
F2 (g) + 2 e- 2 F- (aq) +2.866
6) (Refer to Table 18.1) Will the following reaction occur spontaneously as written?
Cu2+ (aq) + Fe (s) Cu (s) + Fe2+ (aq)
A) no B) yes C) impossible to tell
Answer: B
7) (Refer to Table 18.1) Which metal listed would make the best sacrificial anode?
A) Fe B) Mg C) Cu D) Pb E) Ag
Answer: B
8) (Refer to Table 18.1) Which is the most easily oxidized?
A) Cu B) Mg C) Fe D) H+ E) Cl-
Answer: B
9) (Refer to Table 18.1) Calculate the value of Keq at 25° C for the reaction:
F2 (g) + 2 I- 2 F- (aq) + I2 (g)
A) 5.3 × 1039 B) 5.6 × 1078 C) 2.6 × 1039 D) 1.4 × 10-79 E) 2.33 Answer: B
10) (Refer to Table 18.1) A voltaic cell has a copper electrode in 1 M CuSO4 and a silver electrode in 1 M AgNO3.
11) (Refer to Table 18.1) Which is the best reducing agent?
A) Pb B) F- C) Fe2+ D) Mg E) Ag
Answer: D
12) In the process of electroplating a metal spoon with silver metal, the spoon is the A) anode.
B) cathode.
C) salt bridge.
D) Both A nd B are correct.
E) none of the above Answer: B
13) What mass, in g, of copper will be deposited from a solution of Cu2+ by a current of 2.50 A in 2.00 h?
A) 5.93 B) 1.65 C) 11.9 D) 23.7 E) 0.187
Answer: A
14) Balance the following half-reaction under basic conditions and indicate the coefficient of water and the side of the reaction to which it is added.
HCHO + MnO2 (s) MnO4- + CH3OH
A) 4, left B) 1, right C) 3, left D) 2, left E) 2, right
Answer: D
15) In the plot of ln(k) versus 1/T for a first order reaction, the frequency factor (A) can be determined by A) the intercept of the x-axis.
B) the negative of the slope of the line times R.
C) the intercept on the y-axis.
D) the slope of the line.
E) the slope of the line times R.
Answer: C
16) How many coulombs of charge are required to produce 100. g of Al from Al3+?
A) 3.71 B) 3.56 × 105 C) 1.11 D) 3.21 × 106 E) 1.07 × 106
Answer: E
17) Determine the nuclide that undergoes decay to form238U.
A) Pu242
B) None of above C) Th238
D) Pu238 E) Th242 Answer: A
18) Predict the products from the electrolysis of concentrated, aqueous NaCl.
A) H2 (g), O2 (g) B) Na+ (aq), Cl2 (g) C) Na (s), Cl2 (g) D) H2 (g), Cl2 (g)
E) Na (s), O2 (g) Answer: D
19) What is the identity of the missing species in the following reaction?
14N + 4He 1H + ???
A) 19F B) 17N C) 17O D) 18O E) 19O
Answer: C
20) Balance the following half-reaction (assume an acidic solution) and indicate the number of electrons involved and whether the process is one of oxidation or reduction.
NO2 NO A) 2 e-, reduction
B) 4 e-, oxidation C) 1 e-, reduction D) 2 e-, oxidation E) 3 e-, reduction Answer: A
21) What is the product formed from 232Th by -particle emission?
A) 232Ra B) 228Ra C) 232Ac D) 228Ac E) 228Th
Answer: B
22) A concentration cell consists of two Ni / Ni2+ electrodes. The electrolyte in half-cell A is 0.50 M and the electrolyte in half-cell B is 0.0025 M. Which combination below correctly pairs the anode and the cell voltage?
A) B, + 0.14 B) A, + 0.068 C) B, + 0.068 D) A, - 0.068 E) A, + 0.14 Answer: C
23) Write the net equation for the redox reaction that occurs in the voltaic cell.
Cu (s) / Cu2+ (aq) // Ag+ (aq) / Ag (s)
A) Cu2+ (aq) + 2 Ag (s) Cu (s) + 2 Ag+ (aq) B) Cu(s) + Cu2+ (aq) 2 Ag+ (aq) + Ag (s) C) Cu (s) + 2 Ag+ (aq) Cu2+ (aq) + 2 Ag (s) D) 2 Ag+ (aq) + Ag (s) Cu (s) + Cu2+ (aq)
24) Given the following information:
Fe3+ (aq) + H2 (g) 2H+ (aq) + Fe2+ (aq) E° cell = 0.77 Determine E° for the reaction: e- + Fe3+ (aq) Fe2+ (aq).
A) -0.77 B) 1.54 C) 0.77 D) 0.39
E) additional information is required Answer: C
25) Balance the following half-reaction in a basic solution and indicate the number of electrons involved and whether the process is one of oxidation or reduction.
As (s) AsO2- A) 4 e-, oxidation
B) 2 e-, oxidation C) 3 e-, reduction D) 2 e-, reduction E) 3 e-, oxidation Answer: E
26) Which of the species in the following electrochemical reaction is reduced?
OH O
3 CH3CHCH3 + Cr2O72- + 8 H+ 3 CH3CCH3 + 2 Cr3+ + 7 H2O
A) OH
CH3CHCH3
B) H+ C) Cr3+ D) Cr2O72- E) H2O
Answer: D
27) Which of the following species is reduced in the reaction shown below?
HCHO (aq) + MnO2 (aq) MnO4- (aq) + CH3OH (aq)
A) CH3OH (aq) B) MnO2 (aq) C) H2O (l) D) HCHO (aq) E) MnO4- (aq)
Answer: D
1 MeV = 1.602 × 10-13 J 1 u = 931.5 MeV 1 u = 1.661 × 10-27 kg c = 3.00 x 108 m s-1
Figure 19.1 28) (Refer to Figure 19.1.) Given the exact atomic masses:
199Bi (198.9784) 4He (4.0026) + 195Tl (194.9698) calculate the energy associated with the -decay of 199Bi, in kJ/mol.
A) 5.4 × 108 kJ/mol B) 1.8 × 10-8 kJ/mol C) 1.8 kJ/mol D) 6.3 kJ/mol
E) 8.2 × 106 kJ/mol Answer: A
29) Which of the following emissions is common in carbon-14?
A) -emission B) -ray emission C) -emission D) positron emission
E) electron capture Answer: C
30) What is the identity of the missing species in the following reaction?
35Cl + 1n 35S + ???
A) 1He B) 1e C) 0H D) 1n E) 1H
Answer: E
31) Determine the number of electrons transferred in the following reaction.
2 Mn2+ (aq) + 5 Cl2 (g) + 8 H2O 2 MnO4- (aq) + 16 H+ (aq) + 10 Cl- (aq)
A) 5 B) 2 C) 16 D) 10 E) 7
Answer: D
32) It has been estimated that carbon-14 dating is not useful for objects that are older than 50,000 years. Assuming that the half-life for carbon-14 is 5730 years and that there are 15 disintegrations per minute in living
organisms, how many disintegrations per minute will there be in an object that is 50,000 years old?
33) When the following half-reaction is balanced, the number of electrons and the type of process (oxidation or reduction) is
Cl2 (g) Cl- (aq)
A) 3, reduction. B) 1, reduction. C) 1, oxidation. D) 2, oxidation. E) 2, reduction.
Answer: E
34) Identify the nuclide that would be formed from the -ray emission of fermium-250.
A) 250100Fm B) 250m100Fm C) 25099Es D) 251100Fm E) 23090 Th Answer: A
35) For the reaction:
2 In (s) + 6 H+ (aq) 2 In3+ (aq) + 3 H2 (g) E° = + 0.34 V Determine the value of E° for the half reaction: In3+ (aq) + 3 e- In (s).
A) -0.34 B) 0.34 C) 0.17 D) -0.17
E) none of these Answer: A
36) What is the identity of the missing species in the following reaction?
31P + 4He 1n + ???
A) 17Si B) 27Al C) 34Cl D) 35Cl E) 34S
Answer: C
37) Which of the following nuclides would be most likely to decay by positron emission?
A) 32P B) 26Na C) 28P D) 27Mg E) 22F
Answer: C
38) Which of the following aqueous solutions will yield the greatest mass of metal (at STP) at a platinum anode when the same amount of electric charge is passed through each of them?
A) NaCl B) Cu2+ C) AgNO3 D) Pb(NO2)2 E) Fe3+
Answer: C
39) How many grams of silver are deposited from a solution of Ag+ on a tin cathode in 1.25 h by a current of 3.50
A?A) 17.6 B) 438 C) 0.293 D) 0.163 E) 8.80
Answer: A
40) For a certain reaction, the standard free energy change is -80.0 kJ at 300 K and -40.0 kJ at 600 K. For this reaction
A) H is negative, and S is negative.
B) H is positive, and S is positive.
C) H is negative, and S is positive.
D) H is positive, and S is negative.
E) impossible to tell Answer: A
41) When 9Be is bombarded with -particles, 14C is formed. What other particle is involved?
A) B) - C) n D) p+ E) +
Answer: C
42) A sample of radioactive radon-222 was found to have a half-life of 3.823 d. What fraction of the sample will still be radon-222 after 1 week?
A) 18%
B) 28%
C) 14%
D) 7%
E) Not enough information is given to answer this question.
Answer: B
43) Which of the following species is reduced in the reaction shown below?
Cu (s) + Ag+ (aq) Cu2+ (aq) + Ag (s)
A) Cu (s) B) Ag (s) C) Ag+ (aq) D) H2O (l) E) Cu2+ (aq)
Answer: C
44) [more than one answer] Which of the following would you expect to be radioactive:
A) None of above B) C) D)
Answer: C, D
45) The value of for the oxidation reduction reaction Zn(s) + Pb2+ (1.0M) Zn2+ (1.0M) + Pb(s) is + 0.66 V. What is for the reaction Zn(s) + Pb2+ (0.01M) Zn2+(0.1M) + Pb(s) ?
A) +0.66V B) +0.72V C) +0.69V D) +0.63V
Answer: D
46) Which of the following half-reactions is not correct?
A) Cu+ + e- Cu B) Fe3+ + 2e- Fe+
47) Calculate the mass defect in the creation of a nucleus of cobalt-59 from the nucleons it contains. The nuclear mass of cobalt-59 is 58.9332 u. Use 1.0073 u as the mass of a proton and 1.0087 u as the mass of a neutron.
A) 0.5423 u B) 0.4975 u C) 0.5801 u D) 0.0668 u E) 0.5353 u
Answer: A
48) The half-life of a radioactive nuclide is 14 hours. Without doing calculations, estimate how long would it take for a sample to decay to 12% of its present activity?
A) 56 hours B) 14 hours C) 42 hours D) 3 hours E) 28 hours
Answer: C
49) The following redox reaction is conducted with [Al3+] = 0.01 M and [Mn2+] = 3.0 M. What is the new Ecell?
2 Al (s) + 3 Mn2+ (aq) 2 Al3+ (aq) + 3 Mn (s) E°cell = 0.48 V
A) 0.53 V B) 0.32 V C) 0.60 V D) 0.43 V E) 0.16 V
Answer: A
50) What should be the pH of a solution in the cathode half-cell if the following voltaic cell is to have Ecell = 3.000 V?
Li | Li+ (0.1 M) || H+ (?) | H2 (g, 1 atm), Pt Li+ + e- Li E° = -3.040 V
A) 0.0668 B) 1.676 C) 2.351 D) 0.116 E) 0.040
Answer: B
