EXAM 4 Flashcards
Reduction is the
gain of electrons.
loss of electrons.
gain of protons.
loss of protons.
loss of mass.
Oxidation is the
gain of electrons.
loss of electrons.
gain of protons.
loss of protons.
loss of mass.
loss of electrons
What is the oxidation number of chromium in the ionic compound ammonium dichromate, (NH4)2Cr2O7?
+3
+4
+5
+6
+7
+6
On a periodic table, where do you expect to find elements that are good oxidizing agents?
on the right (except for the last group)
in the middle left
in the top left
at the bottom
in the transition metals
on the right (except for the last group)
Where in the periodic table do you find the elements that are the best reducing agents with the most negative standard reduction potentials?
in group 16
on the left
in the middle
at the bottom
in group 17
on the left
Applying a current to a rechargeable battery converts it from ________ cell to ________ cell.
a voltaic; an electrolytic
an electrolytic; a voltaic
a Leclanché; a Nernst
a Nernst; a Leclanché
a Born cell; a Haber
a voltaic; an electrolytic
Which statement is correct about a voltaic cell?
The electron flow in the external circuit is from the positive electrode to the negative electrode.
The electron flow in the external circuit is from the cathode to the anode.
Electrons are transferred from the oxidizing agent to the reducing agent.
Chemical energy is transformed into electrical energy by a spontaneous redox reaction.
Positive ions diffuse through a porous bridge from the cathode compartment to the anode compartment.
Chemical energy is transformed into electrical energy by a spontaneous redox reaction.
Which statement about an anode in a voltaic cell is correct?
Oxidation occurs at the anode.
Reduction occurs at the anode.
Usually, the cathode is a dissolved ion.
In the external circuit, electrons flow toward the anode.
Chemical species can have their oxidation numbers decreased at the anode.
Oxidation occurs at the anode.
The electrodes on batteries are labeled + and -. The ________ is labeled ________, and ________ occurs there.
anode; positive; oxidation
anode; negative; reduction
cathode; positive; reduction
cathode; negative; reduction
cathode; positive; oxidation
cathode; positive; reduction
The electrodes on batteries are labeled + and -. The ________ is labeled ________, and ________ occurs there.
anode; positive; oxidation
anode; negative; oxidation
cathode; positive; oxidation
cathode; negative; reduction
anode; positive; reduction
anode; negative; oxidation
This diagram represents a voltaic cell. In this cell, which species is oxidized?
Cd(s)|Cd2+ (aq)||Fe3+ (aq),Fe2+ (aq)|Pt(s)
Cd(s)
Cd2+ (aq)
Fe2+ (aq)
Fe3+ (aq)
Pt(s)
Cd(s)
This diagram represents a voltaic cell. In this cell, which species is reduced?
Zn(s)|Zn2+ (1.0 M)||Cu2+ (1.0 M)|Cu(s)
Zn(s)
Zn2+ (aq)
Cu2+ (aq)
Cu(s)
C(s)
Cu2+ (aq)
This diagram represents a voltaic cell. What is the balanced electrochemical reaction represented by this cell?
Al(s)|Al3+ (1.0 M)||Cu2+ (1.0 M)|Cu(s)
2Al(s) + 3Cu2+(aq) 2Al3+(aq) + 3Cu(s)
2Al3+(aq) + 3Cu(s) 2Al(s) + 3Cu2+(aq)
2Al(s) + 3Cu2+(aq) 2Al3+(aq) + 3Cu(s)
This diagram represents a voltaic cell. In this cell, which species is the oxidizing agent?
Al(s)|Al3+ (1.0 M)||Cu2+ (1.0 M)|Cu(s)
Cu2+ (aq)
Cu(s)
Al(s)
Al3+ (aq)
Pt(s)
Cu2+ (aq)
If the potential of a voltaic cell is +1.20 V, what is the free-energy change when one mole of electrons is transferred in the oxidation–reduction reaction?
116 kJ
1.20 kJ
-1.20 kJ
-116 kJ
+602 kJ
-116 kJ
If the potential of a voltaic cell is +0.837 V, what is the free-energy change when two moles of electrons are transferred in the oxidation–reduction reaction?
+162 kJ
-162 kJ
-82.0 kJ
+82.0 kJ
+41.0 kJ
-162 kJ
The spontaneous redox reaction in a voltaic cell has
a negative value of Ecell and a negative value of ΔG.
a positive value of Ecell and a positive value of ΔG.
a negative value of Ecell and a positive value of ΔG.
a positive value of Ecell and a negative value of ΔG.
a positive value of Ecell and a value of zero for ΔG
a positive value of Ecell and a negative value of ΔG.
The standard hydrogen electrode is
used to calibrate voltmeters.
used to produce a set of standard reduction potentials.
needed to activate electrochemical cells.
often overlooked in measuring standard reduction potentials.
used to produce a standard cell potential of exactly 1 V.
used to produce a set of standard reduction potentials.
The Nernst equation can be used to calculate
standard cell potentials from standard reduction potentials.
the change in standard Gibbs free energy from standard cell potentials.
cell potentials from standard cell potentials when the conditions of concentration and temperature are not standard.
cell potentials given the temperature and reactant concentrations.
cell potentials from standard oxidation potentials.
cell potentials from standard cell potentials when the conditions of concentration and temperature are not standard.
A concentration cell is constructed by using the same half-reaction for both the cathode and anode. What is the value of standard cell potential, , for a concentration cell that combines a silver anode in contact with 0.10 M silver nitrate and a silver cathode in contact with 0.00003 M silver nitrate? ( Ered=+0.80 V for Ag/Ag+)
-0.21 V
0.00 V
+0.80 V
-0.80 V
+0.21 V
0.00V
Which statement correctly describes a “dead” battery with a voltage of 0?
The free-energy change for the reaction now is < 0.
All the reactants have been converted into products.
The products and reactants now are in equilibrium.
Q<K
cell potential < 0
The products and reactants now are in equilibrium.
What is true when a battery (voltaic cell) is dead?
Ecell= 0 and Q=K
Ecell= 0 and Q=K
Ecell= 0 and Q= 0
Ecell = 0 and Q= 0
Ecell= 0 and K= 0
Ecell= 0 and Q=K
A concentration cell is constructed by using the same half-reaction for both the cathode and anode. What is the value of Ecell for a concentration cell that combines silver electrodes in contact with 0.10 M silver nitrate and 0.00003 M silver nitrate solutions? ( Ered=+0.80 V for Ag/Ag+)
+0.21 V
+0.59 V
+0.80 V
-0.21 V
+1.01 V
+0.21V
A typical 1.5 V AAA battery has a capacity of 1 ampere-hour (A × hr.). How much energy can such a battery supply?
5400 J
1.5 J
3600 J
1800 J
90 J
5400 J
A typical hearing aid battery has a capacity of 5 ampere-hour (A × hr.) and can supply up to 23.4 kJ of energy. What is the voltage of the battery?
78 V
1.3 V
1.3 × 10-3 V
7.8 × 10-3 V
0.90 V
1.3 V
What is the mass of copper used if it was oxidized to copper(II) over 35.0 s, given the average electrical current delivered was 200. A?
1.02 × 10-1 g
1020 g
2.30 g
4.60 g
1.00 g
2.30 g
If, in using a lead-acid battery to start a car, 1.00 g of Pb is consumed on the anode, how long will it take to recharge the battery, using a current of 0.500 A, and turn the PbSO4 that was produced back into Pb?
15.5 min
1864 min
31.1 min
21.2 min
42.4 min
31.1 min
The unit of current, ampere (A), is defined as
1 C.
1 C/s.
1 mol of electrons.
1 mol of electrons per second.
96,500 C/s.
1 C/s.
The unit of electrical power, watt (W), is defined as
1 C.
1 V.
1 J.
1 C V.
1 C V/s.
1 C V/s.
1.0 kilowatt hour =
1000 J.
6000 J.
3600 kJ.
3600 J.
6000 kJ.
3600 kj.
The peak in nuclear binding energy occurs for an isotope of
helium.
iron.
uranium.
carbon.
lead.
iron.
Light elements with Z< 20 generally have a neutron/proton ratio about equal to
0.5.
0.8.
1.0.
1.3.
1.5.
1.0.
The most naturally abundant nuclides are those that
have an odd number of protons and an odd number of neutrons.
have an even number of protons and an even number of neutrons.
have noble gas configurations of electrons.
can be produced by fission reactions.
can be produced by fusion reactions.
have an even number of protons and an even number of neutrons.
All elements with Z> 83 are
synthetic.
produced by nuclear fission.
radioactive.
not found in nature.
unreactive.
radioactive.
Which of the following nuclides (carbon-14, sodium-24, silicon-26, aluminum-27, and/or phosphorus-31) are most likely to be unstable because they have too many neutrons?
only carbon-14
only carbon-14 and sodium-24
only sodium-24 and silicon-26
only silicon-26, aluminum-27, and phosphorus-31
all of these
only carbon-14 and sodium-24
Which of the following nuclides (nitrogen-15, boron-8, oxygen-18, fluorine-19, and/or magnesium-28) are most likely to be unstable because they have too many neutrons?
only nitrogen-15 and boron-8
only boron-8 and oxygen-18
only oxygen-18 and fluorine-19
only oxygen-18, fluorine-19, and magnesium-28
all of these
only oxygen-18 and fluorine-19
What particle is emitted when iodine-137 decays to xenon-137?
α particle
neutron
proton
positron
β particle
β particle
Which process converts a neutron into a proton?
beta emission
positron emission
electron capture
alpha emission
gamma emission
beta emission
Positron emission is associated with
the conversion of a neutron to a proton.
the conversion of a proton to a neutron.
an increase in mass number.
a decrease in mass number.
the emission of γ rays.
the conversion of a proton to a neutron
Nitrogen-13 decays by positron emission to produce
carbon-13.
oxygen-17.
boron-11.
carbon-14.
boron-13.
carbon-13.
Thallium-206 decays by β decay to produce
gold-202.
lead-206.
polonium-209.
mercury-206.
platinum-208.
lead-206.
Curium-242 (Cm-242) decays by α decay to produce
plutonium-242.
uranium-240.
berkelium-242.
californium-238.
plutonium-238.
plutonium-238.
The activity of a radioactive sample is the number of decay events per second. The SI unit of activity is the becquerel (1 Bq = 1/s). An older unit for activity is the curie (1 Ci = 3.70 × 1010/s). What is the activity in Bq of a sample with an activity of 47 μCi of radiation?
7.9 × 102 Bq
7.9 × 108 Bq
1.7 × 1012 Bq
1.7 × 106 Bq
1.3 × 10-16 Bq
1.7 × 106 Bq
The activity of a radioactive sample is the number of decay events per second. The SI unit of activity is the becquerel (1 Bq = 1/s). An older unit for activity is the curie (1 Ci = 3.70 × 1010/s). What is the activity in μ Ci of a sample with an activity of 2.1 × 105 Bq of radiation?
7.8 × 109μCi
5.7 μCi
5.7 × 10-12μCi
5.7 × 10-6μCi
0.21 μCi
5.7 μCi
A person’s body generates about 0.2 μCi of radioactivity. Determine the total radioactivity emitted by 300 students in a lecture hall. (1 Ci = 3.7 × 1010 Bq and 1 Bq = 1 decay/s)
2 × 106 decays/s
9 × 1016 decays/s
70 decays/s
2 × 107 decays/s
7 × 103 decays/s
2 × 106 decays/s
Radon-222 has a half-life of 3.8 days. A sample from a basement in Colorado was analyzed 5.0 days after it was collected and was found to have an activity of 0.17 Bq. What was the original activity of this sample?
0.22 Bq
0.32 Bq
0.42 Bq
0.62 Bq
0.52 Bq
0.42 Bq
Radiation seed therapy is a common method for treating some prostate cancers and brain tumors. Palladium-103, which decays by electron capture and gamma ray emission with a half-life of 17.0 days, is one isotope used for this treatment. How much palladium-103 (102.91 g/mol) is needed to produce an initial radioactivity level of 1.30 mCi? Note: 1 Ci = 3.70 × 1010/s.
0.0174 μg
0.0251 μg
0.0316 μg
0.0995 μg
0.0594 μg
0.0174 μg
Radioactive decay is a ________-order process.
zero
first
second
zero or first
zero, first, or second
first
Tritium (3H) is used in glowing “EXIT” signs located where there is no electricity for lightbulbs. If the half-life of tritium is 12.26 years, what percentage of the original quantity of the isotope is left in the sign after 18.5 years?
0.632%
63.2%
35.1%
1.51%
25.0%
35.1%
Iodine-131 has a half-life of 8.1 days and is used as a tracer for the thyroid gland. If a patient drinks a sodium iodide (NaI) solution containing iodine-131 on a Tuesday, how many days will it take for the concentration of iodine-131 to drop to 5.0% of its initial concentration?
19 days
0.81 day
8.1 days
35 days
4.3 days
35 days
Carbon-14 measurements on the linen wrappings from the Book of Isaiah on the Dead Sea Scrolls indicated the scrolls contained about 79.5% of the carbon-14 found in living tissue. Approximately how old are these scrolls? The half-life of carbon-14 is 5730 years.
570 years
820 years
1300 years
1900 years
4600 years
1900 years
A 10.00 g sample of wood from an archaeological site produced 3072 β particles in a 10-hour measurement owing to the presence of carbon-14, while a 10.00 g sample of new wood produced 9216 β particles in the same period of time. The half-life of carbon-14 is 5730 years. How old is the wood from the archaeological site?
5730 years
2865 years
4040 years
9080 years
The correct answer differs by more than 100 years from the values given in the answer choices.
9080 years
In 2002, a wooden beam from the Wupatki Indian ruins in Arizona was found to contain 235 mg of carbon-14. A sample of wood of the same mass cut sometime in 2002 contained 264 mg of carbon-14. When was the beam from Wupatki cut if the half-life of carbon-14 is 5730 years?
1974 C.E.
750 C.E.
959 C.E..
1042 C.E.
926 C.E.
1042 C.E.
A rock from the moon was found to contain 1.0 × 10-5 g of uranium-238 and 4.0 × 10-6 g lead-206. All of the lead-206 came from the decay of uranium-238. The half-life for this decay is 4.5 × 109 years. How old is this rock?
1 × 10^6 years
2 × 10^7 years
4 × 10^8 years
3 × 10^9 years
5 × 10^10 years
3 × 10^9 years
Which of the following units is used to quantify the biological effects of radiation?
curies
rems
rads
becquerels
joules
rems
The dominant mechanism through which radiation damages biological tissue and living organisms is by
overheating the tissue.
making the tissue radioactive.
directly breaking bonds in DNA.
directly ionizing biological molecules.
ionizing water and producing hydroxy radicals.
ionizing water and producing hydroxy radicals.
Which type of radiation does the most tissue damage, but only when the emitter is internally ingested?
alpha
beta
gamma
neutron
positron
alpha
Which type of radiation has the greatest penetration ability?
alpha
beta
gamma
neutron
positron
gamma
Which type of radiation has the lowest penetration ability?
alpha
beta
gamma
neutron
positron
alpha
Cardiac pacemakers once used plutonium-238 as a power source. Plutonium-238 decays by the emission of gamma rays and alpha particles. This emission is not especially harmful because
gamma rays are not absorbed very strongly by biological tissue, and alpha particles do not penetrate beyond the container.
gamma rays and alpha particles are the least dangerous forms of radiation.
gamma rays and alpha particles do not penetrate beyond the container.
gamma rays are absorbed by the container, and alpha particles do not affect biological tissue.
tissue damage caused by gamma rays and alpha particles is rapidly repaired by enzymes.
gamma rays are not absorbed very strongly by biological tissue, and alpha particles do not penetrate beyond the container.
Though uranium-238 is radioactive, it can be worked with safely in a glovebox with no additional precautions. This is because
uranium-238 emits gamma rays and they are not absorbed very strongly by biological tissue.
uranium-238 emits alpha particles which are weakly penetrating and do not reach beyond the glovebox.
gamma rays and alpha particles emitted by the uranium-238 do not penetrate beyond the glovebox.
the half-life of uranium-238 is so long that minimal radiation is emitted.
the nitrogen atmosphere of the glovebox inhibits radioactive decay.
uranium-238 emits alpha particles which are weakly penetrating and do not reach beyond the glovebox.
Uranium-235 is the fuel in nuclear power plants. When a nucleus of uranium-235 captures a neutron, the nucleus splits into two lighter nuclei and initiates a chain reaction. The chain reaction is driven by the emission of
protons.
neutrons.
positrons.
β particles.
α particles.
neutrons.
The major fissionable isotope of uranium used in nuclear power plants is
uranium-238.
uranium-236.
uranium-235.
uranium-234.
uranium-235 and uranium-238.
uranium-235.
Electricity is produced from nuclear reactions by
capturing the electrons that are emitted.
accelerating electrons with rapidly moving protons from the nuclear reaction.
a process still not understood by scientists.
using the energy to make steam to turn turbines.
using the energy to accelerate electrons in wires
using the energy to make steam to turn turbines.
The purpose of control rods in a fission reactor is to
cool down the reactor fuel.
prevent oxygen from reaching the fuel.
absorb the neutrons generated in the fission process.
absorb the electrons emitted in the fission process.
enhance the neutron capture process.
absorb the neutrons generated in the fission process.
A barrel of oil produces about 5.9 × 106 kJ of energy. The fission of 235 g of uranium-235 releases 2.1 × 1010 kJ of energy. How many barrels of oil are equivalent to 1 kg of uranium-235?
3560
15,100
836,600
110,000
55,000
15,100
