week 10 chem
The half-life of a first-order reaction is 30.0 seconds. What is the rate constant k for the reaction?
0.0231s−1
32P is an isotope that is sometimes used as a marker in biochemical applications. It has a half-life of about 14.29 days. What is the rate constant for it's nuclear decay?
0.04851 days−1
A first-order reaction has a rate constant k of 3.88 hr−1. If the initial concentration of the reactant is 4.25 M, what is the half-life of the reaction?
0.179
A worker in a high-energy particle accelerator facility is inadvertently exposed to 52rem of proton radiation. What is the number of grays (Gy) to which this is equivalent? Use a relative biological effectiveness of 2 for proton radiation.
0.26
The initial concentration of A in the first-order reaction A→2B+4C is 0.509 mol L−1. Given that the rate constant is 0.821 s−1, what is the half-life of the reaction?
0.844 s
Express 3.00 curies in terms of disintegrations/second. Round your answer to three significant figures. Write your answer in scientific notation.
1.11×10^11 disintegrations per second
The rate constant of the first-order reaction A→4B+2C is 0.600 s−1. What is the half-life of the reaction given that [A]0=0.567 mol L−1?
1.155
The first-order reaction A→2B+C has rate constant 0.538 s−1. If the initial concentration of A is 0.867 mol L−1, what is the half-life of the reaction in seconds?
1.29
1.37 J of alpha radiation is targeted on 1.00 g of fibrotic heart tissue during curative therapy. What is this in grays (Gy)? Your answer should have three significant figures.
1.37 X 10^3 OR 1370
The initial concentration of A in the first order reaction A→3B+2C is 0.535 mol L−1. Given that the rate constant is 0.450 s−1, what is the half-life of the reaction in seconds?
1.54
If an atom has a mass number of 18 and an atomic number of 10, then how many protons and neutrons does it contain?
10 protons, 8 neutrons If the mass number is 18 and the atomic number is 10 (number of protons) then there are 10 protons and 8 neutrons (18−10=8).
When 100rem=1Sv, express 10Gy of alpha radiation in terms of rem.
10,000rem
Calculate the radiation dose of 11.02jkg of tissue in the units of radiation absorbed dose.
1102 rad 11.02 x 100
A sample of iodine-131 was used in a procedure 24 days ago and now 1.50 mCi remain. What was the size of the original sample? (Iodine-131 has a half life of 8 days.) Use three significant figures in your answer.
12.0
On average, how many times would a U.S. resident have to fly across the Atlantic to match the radiation exposure from one year of natural background radiation? Your answer should have two significant figures (round to the nearest tens place).
120 From the chart, the average annual exposure from natural background radiation is 310REM. The exposure from a single transatlantic flight is 2.5REM. Therefore, the background exposure is about 310REM2.5REM=124 times greater than a transatlantic flight. The answer should have two significant figures, so round to 120.
Iodine-123 is a radioisotope that is also used in medical imaging. It is more expensive than iodine-131, but it also emits primarily γ-radiation, while iodine-131 emits most of its energy as β-radiation. The decay of iodine-123 involves electron capture, where a proton in the nucleus is transformed into a neutron. What isotope is produced by this process for iodine-123? Give both the mass number and atomic number by using the nuclide format button to enter your answer in the format AZX.
123/52 Te
A first-order reaction has a rate constant of 0.00489 s−1. What is the half-life of the reactant in seconds? Remember to use correct significant figures in your answer (round your answer to the nearest whole number). Do not include units in your response.
142
A sample of carbon-14 has been decaying for 28,650 years and is now 46.0 grams. What was the size of the original sample? (The half-life of carbon-14 is 5,730 years.) Use three significant figures in your answer.
1472 28,650 / 5730 = 5 46x2 46->92->184 etc....
Useful nuclear fusion reactions require temperatures of at least
15,000,000 K
A sample of copper-64 was used in a procedure to study copper metabolism 65 hours ago and now 0.50 mCi remain. What was the size of the original sample? (Copper-64 has a half life of 13 hours.)
16
A sample of technetium-99 was used in a procedure to image the heart muscle of a patient 36 hours ago and now 2.50 mCi remain. What was the size of the original sample? (Technetium-99 has a half life of 6 hours.)
160
Carbon-14 has a half life of 5,730 years. Which of the following could be the age of a sample that was dated by its C-14 content?
17,000 yr
The initial concentration of A in the first-order reaction A→4B+C is 0.318 mol L−1. Given that the rate constant is 0.31 s−1, what is the half-life of the reaction?
2.2
The initial concentration of A in the first-order reaction 4A→4B+C is 0.933 mol L−1. Given that the rate constant is 0.310 s−1, what is the half-life of the reaction in seconds?
2.24
A worker at a nuclear facility was accidently exposed to radiation and absorbed a total of f 0.20 J of alpha particle radiation, which has an RBE of 10. If his mass is 80.0 kg, what was the radiation dose in rem? Round your answer to two significant figures (round to the nearest tenth).
2.5
Radium-221 will undergo α decay according to the following equation. Ra88221⟶He24+XZA What is the atomic symbol for the unknown nuclide? Enter the atomic symbol for the unknown nuclide in the form XZA, where A is the mass number, Z is the atomic number, and X is the element symbol.
217/86 Rn
A sample of iodine-131 was used in a procedure 32 days ago and now 1.50 mCi remain. What was the size of the original sample? (Iodine-131 has a half life of 8 days.) Use three significant figures in your answer.
23.8
Determine the number of electrons in an atom of manganese.
25
A sample of copper-64 was used in a procedure to study copper metabolism 39 hours ago and now 3.50 mCi remain. What was the size of the original sample? (Copper-64 has a half life of 13 hours.)
28.0
Technitium-99m is used for medical imaging applications, but it must be synthesized on-site due to its relatively short half-life of about 6.0 hr. How much of a 24 g samples of 99mTc would be remaining 18 hours after it was prepared if it is not used?
3.0
The initial concentration of A in the first-order reaction A→3B+C is 0.514 mol L−1. Given that the rate constant is 0.206 s−1, what is the half-life of the reaction?
3.36
Complete the following conversion. 1curie= __________ Bq
3.7×10^10
A 5g tumor is irradiated with high-energy X-rays and absorbs a total of 0.2J of energy. What is the absorbed dose in grays?
40
A sample of technetium-99 was used in a procedure to image the heart muscle of a patient 24 hours ago and now 2.50 mCi remain. What was the size of the original sample? (Technetium-99 has a half life of 6 hours.) Use three significant figures in your answer.
40.0
A sample of carbon-14 has been decaying for 17,190 years and is now 52.0 grams. What was the size of the original sample? (The half-life of carbon-14 is 5,730 years.)
416
If the decay constant for 14C is 1.210×10−4 yr−1, and the natural rate of decay is 13.60 disintegrations/min/g C, what is the age (in years) of an object that exhibits 8.200 disintegrations/min/g C?
4181
A sample of iodine-131 was used in a procedure 40 days ago and now 1.50 mCi remain. What was the size of the original sample? (Iodine-131 has a half life of 8 days.) Use three significant figures in your answer.
48.0
Nuclear reactors require uranium that has been enriched to be about what percentage U-235?
5%
A sample of copper-64 was used in a procedure to study copper metabolism 52 hours ago and now 3.50 mCi remain. What was the size of the original sample? (Copper-64 has a half life of 13 hours.)
56.0
Nitrogen-13 is an unstable isotope with a decay constant k=1.16×10−3 s−1. What is its half-life?
598 s
A sample of carbon-14 has been decaying for 22,920 years and is now 46.0 grams. What was the size of the original sample? (The half-life of carbon-14 is 5,730 years.) Use three significant figures in your answer.
736
A sample of carbon-14 has been decaying for 22,920 years and is now 52.0 grams. What was the size of the original sample? (The half-life of carbon-14 is 5,730 years.) Use three significant figures in your answer.
823
What nuclide, when bombarded by an α particle, will generate carbon-12 and a neutron?
9/4Be
The percentage of the fuel in a nuclear fission reactor that remains in the fuel rods as fission products and unused fuel is _______. Select the correct answer below: 50% 99.9% 100% 0.3%
99.9%
The mass of a nuclide is typically symbolized by which of the following?
A
Which description best fits the definition of daughter nuclide?
A daughter nuclide is a nuclide produced by the radioactive decay of another nuclide.
In the notation for nuclide symbols, mass number is symbolized by the letter:
A is the symbol for mass number. Z represents the atomic number, and N and M don't mean anything in a nuclide symbol.
Which of the following factors influence the effects of radiation on the human body? Select the best answer. Select the correct answer below: the type of radiation the length of exposure to the radiation the location of source of the radiation all of the above
ALL OF THE ABOVE
If mercury-201 undergoes electron capture, what nuclide will result? Enter answer using the element symbol and isotope information, for example mercury-201 would be Hg - 201.
Au - 201
Of the following, which are used to make control rods of a nuclear reactor? Select all that apply: Cadmium Boron Hafnium Plutonium
Cadmium Boron Hafnium
Which of the following best describes the process of gamma (γ) emission?
Gamma (γ) emission is the decay of an excited-state nuclide accompanied by emission of a γ ray.
Which of the following are devices used to detect and measure radiation? Select all that apply: Geiger counters scintillation counters becquerels sieverts radiation dosimeters
Geiger counters scintillation counters radiation dosimeters
Which of the following are able to absorb neutrons without undergoing fission? (select all that apply) Select all that apply: Hafnium Cadmium Plutonium Uranium
Hafnium Cadmium
Which of the following are sites for nuclear fusion? Select all that apply: Inside the sun Inside the earth's core Inside some thermonuclear weapons Inside all stars
Inside the sun Inside some thermonuclear weapons Inside all stars
Which of the following is true of positron emission?
It increases the nuclide's neutron:proton (n:p) ratio.
Which statements below that is true of β decay?
It is most likely to occur when the neutron:proton (n:p) ratio of the nuclide is too large.
How is cobalt-60 obtained for use in radiation treatment?
It is prepared by irradiating cobalt-59 with neutrons.
When considering the conditions under which nuclear fusion occurs, which of the following is true? (select all that apply) Select all that apply: Matter is present in the plasma state. Matter is present in the gas state. A temperature of at least 1,500 K has been achieved. A temperature of at least 15,000,000 K has been achieved.
Matter is present in the plasma state. A temperature of at least 15,000,000 K has been achieved.
Nuclear fusion is described by which of the following? Select the correct answer below: Nuclear fusion is the combination of very light nuclei into heavier nuclei, accompanied by the conversion of mass into large amounts of energy. Nuclear fusion is a phenomenon exhibited by an unstable nucleon that spontaneously converts into a nucleon that is more stable. Nuclear fusion is the breakdown of an unstable nucleus into two smaller nuclei. None of the above
Nuclear fusion is the combination of very light nuclei into heavier nuclei, accompanied by the conversion of mass into large amounts of energy.
Which statements about nuclear fusion are true? Select all that apply. Select all that apply: Nuclear fusion releases more energy than nuclear fission. Nuclear fusion occurs readily at room temperature. Nuclear fusion is combining light nuclei into heavier ones, and nuclear fission is breaking a large nucleus into smaller ones. Nuclear fusion does not occur outside the laboratory.
Nuclear fusion releases more energy than nuclear fission. Nuclear fusion is combining light nuclei into heavier ones, and nuclear fission is breaking a large nucleus into smaller ones.
What kind of decay must carbon-11 undergo to generate boron-11?
Positron emission
Which of the following CANNOT be produced from the fission of uranium-236? Select the correct answer below: Cs-137 Br-87 Pu-239 La-136
Pu-239
Which of the following radioactive isotopes has the longest half-life? Uranium-238 Carbon-14 Potassium-40 Rubidium-87
Rubidium-87 Carbon-14 has a half life of approximately 5800 years, uranium-238 has a half-life of 4.5 billion years, potassium-40 has a half-life of 1.25 billion years, and rubidium-87 has a half life of 48.8 billion years. Therefore, rubidium-87 has the longest half-life.
Which unit of radiation measurement takes into account the relative damage done by the radiation?
Sievert (Sv)
In a nuclear reaction, what is rearranged?
Subatomic particles
Why is Tc-99m made on-site?
The half-life is too short
Which is true about the nucleus? Select the correct answer below: Most of the volume of an atom is taken up by the nucleus. Electrons are examples of nucleons. The number of protons in the nucleus is called the atomic number (Z) of the element. The force that holds the nucleus together is called the weak nuclear force.
The number of protons in the nucleus is called the atomic number (Z) of the element.
Which radioactive isotope is used in nuclear fuels? Select the correct answer below: C-14 Co-60 U-235 Cs-137
U-235
Which of the following was used to determine the age of the earth?
U-238
Which of these is a nucleus that can be used for radiometric dating?
U-238
In the notation for nuclide symbols, atomic number is symbolized by the letter:
Z is the symbol for atomic number, or the number of protons. A represents the mass number.
In the sun, the fusion of four hydrogen nuclei produces two positrons, along with which of the following?
a helium nucleus
When a 2H nucleus fuses with a 3H nucleus, which of the following is produced? Select the correct answer below: two helium nuclei a helium nucleus and two protons a helium nucleus and two positrons a helium nucleus and a neutron
a helium nucleus and a neutron
Which characteristics of a radioisotope make it good for medical imaging applications (so it can be used as a radioactive tracer)? Select all that apply. a very short half-life (less than one second) a moderate half-life (a few hours to a few days) a very long half-life (many years) emits primarily α-radiation emits primarily γ-radiation emits primarily β-radiation
a moderate half-life (a few hours to a few days) emits primarily γ-radiation
What type of particle is emitted when U92238 decays to Th90234?
a particle
There are no self-sustaining fusion reactors operating in the world because there is currently a lack of _______. Select the correct answer below: a way to achieve the extremely high temperatures needed for a fusion reaction a method to dispose of the waste produced by fusion reactions a way to contain fusion reactions materials that will participate in fusion
a way to contain fusion reactions
At temperatures at which useful fusion reactions occur: Select the correct answer below: most molecules dissociate into atoms, which then ionize to form plasma all molecules dissociate into atoms, which then ionize to form plasma ions neutralize to form atoms, which then combine to form molecules none of the above
all molecules dissociate into atoms, which then ionize to form plasma
An atomic bomb contains: several pounds of fissionable material a source of neutrons an explosive device all of the above
all of the above
List the radioactive tracers used in medicine. technetium-99 thallium-201 iodine-131 All of the above. None of the above.
all of the above
Which of the following has the highest density? ionic solid atom atomic nucleus these are equally dense
atomic nucleus
Which of the following is included in nuclide symbols, but is not strictly necessary for the identification of the nuclide?
atomic number
When the number of fission reactions ocurring in a bomb increases at an exponential rate, this phenomenon is called a(n): Select the correct answer below: exponential fission chain reaction bulk fission none of the above
chain reaction
Carbon-14 enters living organisms primarily in the form of
co2
The correct order of the reactions, from least to greatest, according to the amount of energy that each generates relative to the mass consumed is: _______. combustion; nuclear fission; nuclear fusion combustion; nuclear fusion; nuclear fission nuclear fission; combustion; nuclear fusion nuclear fission; nuclear fusion; combustion
combustion; nuclear fission; nuclear fusion
A nuclear explosion in a reactor can occur as the result of the failure of which of the following processes? Select all that apply: containment cooling generation of electricity steam generation
containment cooling
In order to explode, an atomic bomb requires a mass of fissionable material above the: Select the correct answer below: subcritical mass critical mass supercritical mass mass defect
critical mass
If you are measuring radioactive emission for a medical application, what would be an appropriate unit of measurement?
curie (Ci)
What is the end product of nuclear reactors? Select the correct answer below: electricity nuclear fuel steam power thermal energy
electricity
Which is the term for the repulsive force between charged nucleons?
electromagnetic force
The reactions that occur in fission reactors are identical to the reactions that occur in fusion reactors.
false
What is the main challenge in building a fusion reactor?
finding a way to contain the fusion reactions
The SI unit for measuring absorbed radiation dose is
gray (Gy)
Carbon-14 forms:
in the nitrogen-rich upper atmosphere
Heavier elements will undergo fission in order to: Select the correct answer below: increase total binding energy decrease total binding energy increase binding energy per nucleon decrease binding energy per nucleon
increase binding energy per nucleon
Half-life expressions can be derived from
integrated rate laws.
α emission is most likely to occur if a nucleus:
is too large
The half-life of a radioisotope is 8.0 seconds. What is the rate constant k for the radioactive decay of this isotope?
k=0.0866 s−1
Nuclear fission typically occurs for:
large nuclei
Atoms of the same element can differ in which of the following?
mass numbers
Atoms of the same element can have different:
mass numbers
After how many half-lives will a substance be completely gone?
none of the above never
The identity of an atom can change during a:
nuclear reaction
The nuclide that emits radiation in nuclear reactions is called the
parent nucleus
At the temperatures necessary for nuclear fusion to take place, matter exists in which state?
plasma
The mass number is essentially the sum of the number of ________ in an atom.
protons and nuetrons
Which of the following are devices used to measure personal exposure to radiation? select all that apply: quartz fiber dosimeters Geiger counters scintillation counters film badges
quartz fiber dosimeters film badges
The following half-life equation is for ___________ order reactions: t12=1k[A]0
second
An amount of fissionable material that sufficient to sustain a chain reaction at a constantly increasing rate is called a: Select the correct answer below: subcritical mass critical mass supercritical mass none of the above
subcritical mass
Which equation below is the correct equation for finding the half-life (t12) of a radioisotope given its rate constant, k?
t1/2=ln2/k
Which of the following is the major source of radon radiation?
uranium in the ground
Which is not a required component of a nuclear reactor? containment system reactor coolant control rods water
water
Which of the four fundamental forces is responsible for nuclear decay?
weak force
What kind of decay must carbon-14 undergo to generate nitrogen-14?
β emission
