Houston Community College System
EXAM # 3
Chemistry 1412
Instructor : Dr. Komala Krishnaswamy
CHEM 1412 EXAM # 3
Name:
Score:
Part I-Please DO NOT circle. Write the correct answer in space provided. (3 points each)
_____1. Given the following standard reduction potentials, choose the strongest reducing agent.
Fe2+ + 2e– → Fe
Mn2+ + 2e– → Mn
Co2+ + 2e– → Co(s)
A. Fe+2
E°red= -0.45 V
E°red= -1.18V
E°red = –0.28 V
B. Mn2+
C. Co+2
D. Fe
E. Mn
D. Fe
E. Mn
_____2. Choose the strongest oxidizing agent:
A. Fe+2
B. Mn2+
C. Co+2
_____3. Consider an electrochemical cell based on the following cell diagram:
Zn | Zn2+(aq)|| MnO2 (s)|Mn+2 (aq) | Pt
Which of the following statements is correct?
A.
B.
C.
D.
E.
The anode is Pt and the cathode is Zn
Zn+2 is oxidized
The oxidizing agent is Zn
MnO2 is reduced
Mn+2 is the cathode
_____4. For the reaction, 3Ag+(aq) + Fe(s) → 3Ag(s) + Fe+3(aq), E° is 0.030V. Calculate
the standard free energy change.
A. -2.89 kJ
B. +2.89 kJ
C. -8.69 kJ
D. 8.69 kJ
E. 5.79 kJ
_____5. Calculate the equilibrium constant for the above cell reaction at 25oC.
A. 3.21
B. 1.66
C. 10.3
D. 2.76
E. 1.0
_____6. K-40 decays by positron emission to form which of the following radioactive nuclide?
A. Ar-39
B. Ar-40
C. Ca-40
D. Ca-39
E. Br-35
D. Zn-67
E. Ga-66
_____7. What is the product of electron capture by Ga-67?
A. Ga-68
B. Ge-67
C. Ge-66
_____8. When Cs-137 undergoes beta decay to form which isotope:
A. Ba-137
B. Xe-137
C. Cs-138
D. Ba-138
E. Xe-136
_____9. In the following nuclear transmutation reaction, 14N (X, p)17O, the particle X is a
A. alpha paricle
B. beta particle
C. neutron
D. proton
E.positron
_____10. When Platinum-190 undergoes alpha decay what product isotope forms?
A. W-190
B. W-186
C. W-188
D. Os-188
E. Os-186
_____11. Calculate the standard EMF, Eo, of a voltaic cell using Al and Mn electrodes given the
following reduction half reactions and their corresponding standard reduction potentials:
Al3+ + 3e– → Fe
Mn2+ + 2e– → Mn
A. -0.48 V
B. 2.62 V
E°red= -1.66 V
E°red= -1.18V
C. -0.22 V
D. 0.22 V
E. 0.48 V
_____12. Addition of which of the following will cause the solubility of AgCl to decrease in
aqueous solution?
A. HNO3(aq)
B. AgNO3(aq)
C. EDTA
D. NH3
E. None of these
_____13. How much of a sample 1.00g sample of 222Rn will remain after 10.0 days?
The half-life of 222Rn of 3.82 days.
A. 0.163g
B. 6.14 mg
C. 0.767 g
D. 1.30 mg
E. 0.544g
_____14. Which of the following are structural isomers of C6H12?
i. Cyclohexene ii. Methylcyclopentane
A. i alone
B. ii & iii
iii. 1-hexene iv. n-hexane
C. i & v
D. iv alone
v. 2-hexyne
E. v alone
_____15. Which of the following are alkynes?
i.C10H22
ii. C8H16
A. All are
iii.C12H24
B. None are
iv. C5H10
C. iv
v. C21H44
D. ii, iii & iv
E. i, v
_____16. The aqueous solubility of which of the following will increase upon the addition of
HNO3(aq)?
A. Mn(OH)3
B. CaCO3
C. Ag2S
D. Mg3(PO4)2
E. all will
_____17. Determine the mass of Fe that can form when 40.0 A current is passed FeCl3(s) for 5.00
Hrs?
A. 0.112 g
B. 139 g
C. 2.31 g
D. 0.0385 g
E. 6.72 g
_____18. The solubility product constant of Al(OH)3 is 3 x 10-34 at 25C. What minimum
concentration of Al+3 is required to bring about precipitation of Al(OH)3 when added
to a solution of pH=8?
A. 3.0 x 10-10M
B. 2.06 x 10-9M
C. 6.7 x 10-6M
D. 3.0 x 10-16M
_____19. What is the name of the following:
A. 2,3-dimethyl-3,3-diethylheptane
C. 4,4-diethyl-2,3-dimethylhexane
E. 3,3-diethyl-2,3-dimethylheptane
B. 1,2,2-triethyl-3,4,4-trimethylbutane
D. 3,3,4-triethyl-1,1,2-trimethylbutane
_____20. The functional groups in lipitor are:
A.
B.
C.
D.
Ester, ketone, phenol, halogen, amine
Ether, carbonyl group, phenol, amine, halogen
Amide, Amine, Carboxyl, alcohol, benzene ring, Halogen
Acid anhydride, amine, phenol, halogen
Part II-Essay questions(Please show all your work for complete credit.
21.The solubility product constant for Mn3(PO4)2 is 1.0 x 10-22 at 25C.
a. Calculate its molar solubility of in pure water.
b. Calculate its molar solubility an aqueous solution that is 0.100 M Na3PO4
22. The solubility product constant of Mn(OH)2 is 2.10 x 10-13 at 25C.
a. Calculate the pH of a saturated aqueous solution of Mn(OH)2.
b. What is solubility of Mn(OH)2 in g/L at this temperature
23. a. Balance the equation for this reaction carried out in a basic solution:
MnO4- + CN -  MnO2 - + CNO-
b. Identify the reducing agent & the oxidizing agent
24. Calculate the nuclear binding energy per nucleon, in joules, for Cu-63 (nuclear mass 62.91367
amu). Additional data: mass of proton= 1.00728 amu, mass of neutron= 1.00867 amu;
1 g = 6.022 × 1023 amu; c = 3.00 × 108 m/s.
25. Consider a voltaic cell based on the following reduction half-reactions:
Cr+3 + 3e– → Cr
E°red= -0.74 V
2+
–
Cd + 2e → Cd
E°red= -0.40V
A. What is the overall cell reaction?
B. Calculate the standard cell EMF
C. Calculate the cell potential when [Cr+3] = 0. 500M & [Cd+2] = 0.125 M
D. Is the reaction spontaneous under these conditions?
Bonus question:
Draw and Name 5 BRANCHED isomers of C7H16