Nuclear chemistry Questions and Answers
Physical Chemistry
Nuclear chemistryIodine-131 is radioactive and has a half life of 8.04 days. What percentage of a sample would be left after 36.4 days?
Round your answer to 2 significant digits.
00
%
×10
x 3 ?
Physical Chemistry
Nuclear chemistryThe potassium-38 nuclide radioactively decays by positron emission. Write a balanced nuclear chemical equation that describes this process.
X
Ś
Y
Physical Chemistry
Nuclear chemistryThe half-life of silicon-32 is 710 years. If 40 grams is present now, how much will be
present in 700 years? (Round your answer to three decimal places.)
Physical Chemistry
Nuclear chemistryCesium-137 is radioactive and has a half life of 30. years. Calculate the activity of a 5.2 mg sample of cesium-137. Give your answer in becquerels and in curies.
Round your answer to 2 significant digits.
Physical Chemistry
Nuclear chemistryThe carbon-11 nuclide radioactively decays by positron emission. Write a balanced nuclear chemical equation that describes this process.
Physical Chemistry
Nuclear chemistryRadium-226 is radioactive and has a half life of 1600. years. How much of a 6.70 mg sample would be left after 3.47 × 10³ years?
Round your answer to 2 significant digits. Also, be sure your answer has a unit symbol.
Physical Chemistry
Nuclear chemistryMERE
Suppose a samarium-147 nuclide decays into a neodymium-143 nuclide by emitting an alpha particle.
2012
Complete the nuclear chemical equation below so that it describes this nuclear reaction.
Physical Chemistry
Nuclear chemistrySuppose a potassium-38 nuclide decays into an argon-38 nuclide by emitting a positron.
Complete the nuclear chemical equation below so that it describes this nuclear reaction.
38
19
1
0
00
Physical Chemistry
Nuclear chemistryThe uranium-238 nuclide radioactively decays by alpha emission. Write a balanced nuclear chemical equation that describes this process.
Physical Chemistry
Nuclear chemistryThe yttrium-88 nuclide radioactively decays by electron capture. Write a balanced nuclear chemical equation that describes this process.
Physical Chemistry
Nuclear chemistryOn your own paper, write the equation for the nuclear reaction described in each of the
following processes:
1. The transmutation that occurs when a scandium-48 nucleus undergoes beta
decay.
2. Americium-241 undergoes alpha decay (inside a smoke detector)
3. Technetium-99 (99mTc) undergoes gamma decay to form 99Tc
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Physical Chemistry
Nuclear chemistryWhat is the ground state of an element?
Select one:
It is the most energetically favorable arrangement of the element's electrons.
It is the arrangement of electrons that occurs at room temperature or below.
It is the arrangement of electrons that occurs after one or more electrons becomes excited.
It is the most energetically favorable arrangement of the element's protons.
Physical Chemistry
Nuclear chemistryTo resolve an object in an electron microscope, the wavelength of the electrons must be close to the diameter of the object. What
kinetic energy, Ek, must the electrons have in order to resolve a protein molecule that is 7.60 nm in diameter? Take the mass of
an electron to be 9.11 x 10-³1 kg.
Ex =
x10
x10
TOOLS
Physical Chemistry
Nuclear chemistry(5 points) In a certain sci-fi movie, machines take over the Earth and use human body heat as
an energy source. If humans are 37°C, and the environment is 20°C, what is the maximum
possible efficiency of this process? Explain your reasoning.
Physical Chemistry
Nuclear chemistry32p has a half-life of 14.3 days. The original sample of 32p has a mass of 1.88mg. Approximately what mass of P-32 will remain after 6 half-lives?
0.188 mg
0.0588 mg
0.352 mg
0.0294 mg
0 0.101 mg
None of the answers are correct.
Physical Chemistry
Nuclear chemistryAn isotope with a half-life of 18.0 seconds was produced in a physics lab as a by-product of a reaction. Exactly how many half-lives pass after 126 seconds have elapsed? Enter only a number.
Physical Chemistry
Nuclear chemistryCurium-240 has a half-life of 27 days. The original sample of curium-240 has a mass of 0.874 mg.
Approximately what mass of Cm-240 will remain after 5 half-lives?
0.175 mg
0.0625 mg
0.135 mg
0.0273 mg
0.361 mg
None of the answers are correct.
Physical Chemistry
Nuclear chemistryWhich of the following statements is true about both nuclear fusion and nuclear fission?
They occur in the sun.
Heavy atoms are split.
Two light nuclei combine.
Some mass changes into energy.
Physical Chemistry
Nuclear chemistryIndium-116 is radioactive and has a half life of 14.10 seconds. Calculate the activity of a 1.9 mg sample of indium-116. Give your answer in becquerels and in curies. Round your answer to 2 significant digits.
Physical Chemistry
Nuclear chemistryConsider the fission of uranium-235.
a. The fission of uranium-235 begins with the addition of a neutron to the nucleus
What isotope is formed? Give the isotope symbol.
b. After the neutron is added, the uranium atom is more unstable and undergoes
fission. A possible set of products is krypton-94, barium-139, and 3 neutrons.
How many protons are in these products?
c. Were any protons lost?
Physical Chemistry
Nuclear chemistryWrite a nuclear equation for the fission of uranium-235 by neutron bombardment to form
antimony-133, three neutrons, and one other isotope.
Physical Chemistry
Nuclear chemistryHow much phosphorus-32 remains from a 8.00 g sample after each of the following number of half-
lives: (a) 3; (b) 9?
g of phosphorus-32 remains.
g of phosphorus-32 remains.
Physical Chemistry
Nuclear chemistryA certain element consists of two stable isotopes.
The first has an atomic mass of 7.0160 amu and a percent natural abundance of 92.58%.
The second has an atomic mass of 6.0150 amu and a percent natural abundance of 7.42 %.
What is the atomic weight of the element?
Physical Chemistry
Nuclear chemistryA wooden object from a prehistoric site has a carbon-14 activity of 10 cpm compared to 40 cpm for new wood. If carbon-14 has a half-life of 5730 yr, what is the age of the wood?
22 900 yr
17 200 yr
1430 yr
5730 yr
11 500 yr
Physical Chemistry
Nuclear chemistryLight gathering power of optical telescopes is dependent on the of the lens.
shape
thickness
size
refractive Index
Physical Chemistry
Nuclear chemistrySplitting of the nucleus of an atom is called
chemical reaction
nuclear fission
nuclear fusion
chemical bonding
Physical Chemistry
Nuclear chemistryBe sure to answer all parts.
Compare the wavelengths of an electron (mass=9.11 × 10-31 kg) and a proton (mass = 1.67 x 10-27 kg), each having (a) a speed of 3.52 x 106 m/s and (b) a kinetic energy of 1.88 × 10-15 J. Enter your answers in scientific notation.
(a) Electron wavelength = __ x 10 __ m
Proton wavelength = __ x 10 __ m
(b) Electron wavelength = __ x 10 __ m
Proton wavelength = __ x 10 __ m
Physical Chemistry
Nuclear chemistryUse the Rydberg equation to calculate the wavelength (in nm) of the photon emitted when an electron in a hydrogen atom undergoes a transition from n = 6 to n = 2.
Physical Chemistry
Nuclear chemistryIdentify the isotope used in farm animals' body composition analysis.
Phosphorous-40
Potassium-40
Calcium-45
Sodium-24
Physical Chemistry
Nuclear chemistryInfrared radiation has frequencies from 3.0×10¹1 to 3.0x10¹4 Hz, whereas the frequency region for X-ray radiation is 3.0×1016 to
3.0×10¹⁹ Hz.
We can say that:
1. The speed of infrared radiation is ___ X-ray radiation.
2. The wavelength of infrared radiation is ____ X-ray radiation.
Physical Chemistry
Nuclear chemistryPlutonium-238 is an a emitter and a compact heat source. Coupled with a PbTe thermoelectric device, it was once used as a very reliable electrical energy source for cardiac pacemakers.
What is the product of the radioactive decay of plutonium-238?
A Thorium-230
B. Uranium-234
C. Californium-246
D. Plutonium-234
238 Pu ⇒ a particle + ?
Physical Chemistry
Nuclear chemistryTwo nitro (NO₂) groups are chemically bonded to a patch of surface. They can't move to another location on the surface, but they can rotate (see sketch at right). It turns out that the amount of rotational kinetic energy each NO, group can have is required to be a multiple of e, where E=1.0 × 10 -24 J. In other words, each NO, group could have e of rotational kinetic energy, or 2e, or 3ɛ, and so forth - but it cannot have just any old amount of rotational kinetic energy. Suppose the total rotational kinetic energy in this system is initially known to be 188. Then, some heat is removed from the system, and the total rotational kinetic energy falls to 14ɛ. Calculate the change in entropy. Round your answer to 3 significant digits, and be sure it has the correct unit symbol. ► Two rotating NO, groups bonded to a surface.
Physical Chemistry
Nuclear chemistryThe first has a mass of 35.0 u and a percent natural abundance of 75.5%.
The second has a mass of 36.9 u and a percent natural abundance of 24.5 %.
What is the atomic mass of the element?
u
Physical Chemistry
Nuclear chemistryCameron is a doctor treating a cancer patient, Billy is an archeologist dating a vase, and Isabelle is a geologist dating a layer of soil. Which isotopes would each person most likely use?
(a) Cameron would use carbon-14, Billy would use cobalt-60 (which releases gamma rays), and Isabelle would useuranium-238.
(b)Cameron would use cobalt-60 (which releases gamma rays), Billy would use carbon-14, and Isabelle would use uranium-238.
(c) Cameron would use uranium-238, Billy would use carbon-14, and Isabelle would use cobalt-60 (which releases gamma rays).
(d) Cameron would use cobalt-60 (which releases gamma rays), Billy would use uranium-238, and Isabelle would use carbon-14.
Physical Chemistry
Nuclear chemistryThe beryllium-10 nuclide radioactively decays by beta emission. Write a balanced nuclear chemical equation that describes this process.
Physical Chemistry
Nuclear chemistryThe table below lists information about two common types of nuclear radiation. Fill in the missing information. Note: round masses to the nearest atomic mass unit (u).
name matter or energy? mass(u) charge(e) can be stopped by
gamma matter ______ _______ __________
energy
________ matter 4 +2 ___________
energy
Physical Chemistry
Nuclear chemistrySuppose an aluminum-27 nuclide transforms into a sodium-24 nuclide by absorbing a neutron and emitting an alpha particle. Complete the nuclear chemical equation below so that it describes this nuclear reaction.
Physical Chemistry
Nuclear chemistryIf a rock sample was found to contain 6.93 x 10^-7 mol of argon-40, how much potassium-40 would also have to be present for the rock 1.3 x 10^9 years old?
The half-life of K-40 is 1.3 x 10^9 years.
______ mol K-40
Physical Chemistry
Nuclear chemistryFind the half-life of a radioactive element, which decays according to the function
A(t) = A₀e‾⁰∙⁰³⁸⁴ᵗ, where t is the time in years.
The half-life of the element is ___________years.
Physical Chemistry
Nuclear chemistryThe technetium-99 nuclide radioactively decays by beta emission. Write a balanced nuclear chemical equation that describes this process.
Physical Chemistry
Nuclear chemistryProperly order the following steps for a U-235 nuclear fission chain reaction
1. 9 neutrons are now able to bombard other U-235 isotopes
2. A neutron bombards a U-235 isotope
3. Two new isotopes are created along with 3 neutrons
4. 3 neutrons bombard 3 other U-235 isotopes
Physical Chemistry
Nuclear chemistryWhat is the process called where 2 H isotopes combine to form an alpha particle, a neutron, and energy?
a. Radioactivity
b. Alpha Decay
c. Nuclear Fusion
d. Chain Reaction
e. Nuclear Fission
Physical Chemistry
Nuclear chemistryIf 12 g of a radioactive substance are present initially and 9 yr later only 6 g remain, how much of the substance will be present after 11 yr?
After 11 yr there will be g of a radioactive substance.
(Round the final answer to three decimal places as needed. Round all intermediate values to seven decimal places as needed.)
Physical Chemistry
Nuclear chemistryWe ended with 15 grams of Xenon-131 and 3 half lives have passed.
a. What element was it originally? (What was its radioactive version)
b. How much of this radioactive element did we originally have? (Hint: This was Beta decay)
Physical Chemistry
Nuclear chemistryIf we started with 65 grams of Gold-198
a. What daughter element will be produced?
b. How much of that element will be present after 4 half lives?
c. How much time has passed?
Physical Chemistry
Nuclear chemistryWhich statement about nuclear reactions is NOT true?
in fission, nuclei are split and in fusion, nuclei are combined
nuclear reactions release small amounts of energy
nuclear reactions involve changing the identity of the atom
in fission, the total mass of the reactants equals the total mass of the products
Physical Chemistry
Nuclear chemistryWhat is the half-life of a 100.0 g sample of nitrogen-16 that decays to 6.25 g of nitrogen-16 in 21.6 s?
64.8 seconds
10.8 seconds
43.2 seconds
7.2 seconds
none of these choices is correct
Physical Chemistry
Nuclear chemistryWrite balanced nuclear equations for the decay of the radioactive particles below.
1. Radon-226 decays to produce an alpha particle and a gamma ray.
2. Gallium-70 decays to produce a beta particle.
Physical Chemistry
Nuclear chemistryComplete the following nuclear equations. Write the mass number, atomic number, and symbol for the remaining particle.
Physical Chemistry
Nuclear chemistryTUTOR
Radiochemical Dating
half-life
rate constant, k
disintegrations per minute (No)
elapsed time (age)
Radiochemical dating works on the principle that the quantity of radiation emitted from a sample is proportional to the quantity of radioactive isotope
present. Therefore, comparing the radioactivity of an old sample (at time t) to that of a new sample (at time 0) can give the ratio of masses (or amounts)
of the radioactive isotope present in each. This ratio can then be used to calculate the time elapsed.
Step 1
Use the half-life to calculate the rate constant for the reaction. All radioactive decay processes are first order, so k = 0.693/t1/2-
Step 2
Experimentally determine the number of disintegrations per minute for the artifact and for carbon in living matter. The ratio of these two values is
equal to N₂/No.
Step 3
Solve for time elapsed.
The carbon-14 activity of an artifact from a burial site was 6.0 min¹g¹. The half-life of carbon-14 is 5730 years, and the current carbon-14 activity is
16.1 min¹g¹ (that is, 16.1 disintegrations per minuts per gram of carbon).
How old is the artifact?
y