Chem103 Exam3
Chem103 Exam3
Chem103 Exam3
Final Exam
5 June 2006
Name ____________________________
____ 2. In how many different pairs can these substances be mixed to produce buffer solutions?
HNO3 NaNO3 NaOH CH 3COOH CH3COONa
a. 2
b. 3
c. 4
d. 5
e. 6
____ 3. A 50.00 mL sample of 0.0950 M acetic acid (Ka = 1.8 × 10-5) is being titrated with 0.106 M NaOH. What is
the pH at the endpoint of the titration?
a. 5.28
b. 7.00
c. 8.72
d. 9.26
e. Need more information to answer
____ 4. Silver chloride has Ksp = 1.8 × 10-10. What is its molar solubility in water?
a. 9.0 × 10-11 M
b. 3.6 × 10-10 M
c. 6.7 × 10-6 M
d. 9.5 × 10-6 M
e. 1.3 × 10-5 M
____ 5. Which group contains only solutes that would decrease the solubility of barium sulfate?
a. HNO3, H2SO4, HCH3COO
b. SO2, CO2, NH3
c. Ba(NO3)2, Na2SO4, H2SO4
d. Ba(OH)2, NaOH, NH4 OH
e. Na2 SO4, NaOH, NaCH3COO
____ 6. If a reaction is product-favored at any temperature, then ΔH° is _________ and ΔS° is _________.
a. positive; positive
b. positive; negative
c. zero; positive
d. negative; positive
e. negative; negative
____ 7. Use the data given to calculate the value of ΔG°rxn for the reaction at 25°C
AgCl(s) Ag+(aq) + Cl-(aq)
a. -75.2 kJ
b. -55.7 kJ
c. +32.5 kJ
d. +55.7 kJ
e. +75.2 kJ
____ 8. What is the value of the equilibrium constant at 25°C for a reaction, if the value of ΔG°rxn is -47.8 kJ at 25°C?
a. 1.70
b. 6.88
c. 2.30 × 102
d. 2.74 × 105
e. 2.37 × 108
____ 10. Use the following list of half-reactions to answer the question. The strongest oxidizing agent in the table is
MnO4-(aq) + 8H+(aq) + 5e- → Mn2+(aq) + 4H2 O( ) +1.51 V
Cr2 O72-(aq) + 6e- → 2Cr3+(aq) + 7H2 O( ) +1.33 V
2+ -
Pt (aq) + 2e → Pt(s) +1.20 V
Cu2+(aq) + 2e- → Cu(s) +0.34 V
Pb2+(aq) + 2e- → Pb(s) -0.13 V
3+ -
Al (aq) + 3e → Al(s) -1.66 V
a. Al(s)
b. Al3+(aq)
c. H+(aq)
d. MnO4-(aq)
e. Mn2+(aq)
____ 11. The most penetrating type of radioactivity is _________ , and the least penetrating is _________.
a. alpha particles; gamma rays
b. beta particles; alpha particles
c. beta particles; gamma rays
d. gamma rays; alpha particles
e. gamma rays; beta particles
____ 12. If polonium-210 emits an alpha particle, the other product will be
a. lead-206.
b. mercury-204.
c. mercury-206.
d. polonium-208.
e. radon-206.
______________.
a. alpha particle
b. beta particle
c. gamma ray
d. neutron
e. positron
____ 16. The half-life of radon-222 is 2.8 days. How many days would it take for the activity due to radon in a tightly
closed building to decrease to 2.8 % of its original value?
a. 1.0
b. 8.9
c. 14
d. 17.8
e. 100
____ 17. Pu can be transmuted into Am by a process involving bombardment by _________ and emission of
_________.
a. a neutron; a beta particle
b. two neutrons; a beta particle
c. a neutron; two beta particles
d. a neutron; an alpha particle
e. two neutrons; an alpha particle
____ 18. The fission reaction exploited in nuclear power stations involves
a. neutron bombardment of uranium-235.
b. neutron bombardment of uranium-238.
c. neutron bombardment of plutonium-239.
d. x-ray irradiation of plutonium-241.
e. x-ray irradiation of uranium-235.
____ 19. Which pair of elements could not be produced from neutron bombardment of uranium-235 if 2 additional
neutrons are also produced?
a. cesium-143 and rubidium-91
b. bromine-87 and lanthanum-147
c. zirconium-97 and barium-139
d. tellurium-137 and zirconium-97
e. iodine-141 and yttrium-93
____ 20. Which of these is the smallest contributor to background radiation exposure in the U.S.?
a. cosmic radiation
b. radon
c. x-rays
d. uranium
e. nuclear wastes
____ 21. The most abundant element in the earth's crust, by mass, is
a. carbon
b. iron
c. nickel
d. oxygen
e. silicon
____ 22. The most abundant metal in the earth's crust, by mass, is
a. Al
b. Ca
c. Fe
d. Mg
e. Na
____ 23. How many of these appear in elemental form on the earth, or in its atmosphere: argon, nitrogen, chlorine,
oxygen, sulfur?
a. 1
b. 2
c. 3
d. 4
e. 5
____ 24. Which of the following is not part of the nitrogen cycle?
a. ammonia
b. nitrous acid
c. nitric acid
d. sodium azide
e. sodium nitrate
____ 25. The most reduced form of nitrogen is _________, and the most highly oxidized form is _________.
a. elemental nitrogen; ammonia
b. elemental nitrogen; the nitrate ion
c. ammonia; elemental nitrogen
d. ammonia; the nitrate ion
e. the nitrate ion; ammonia
Problems
26. (25 points) A saturated MgF2 solution (Ksp = 6.4 x 10-9) is attached to a hydrogen electrode and the resulting
potential is measured to be 2.32 V. Assume the pressure of the H2(g) is maintained at 1 bar.
Research is focused on harnessing fusion reactions to achieve the same purposes. A typical fusion reaction is
2
1H + 31H → 42 He + 10n
Will fusion-based reactors produce more energy than fission-based reactors? Justify your answer with a
comparison of energies.
1
0n: 1.008665 amu
2
1H: 2.014102 amu
3
1H: 3.016049 amu
92
36Kr: 91.926156 amu
141
56Ba: 140.914411 amu
235
92Pu: 235.043930 amu
MULTIPLE CHOICE