PP 29: Nuclear Chemistry
Drill:
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Calculate the solubility of MgF2 in 0.10 M KF.
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A statue is electroplated at the cathode using a silver anode in aqueous AgNO3.
Calculate the current required to plate 10.8 g of silver in 5.00 minutes.
(Ksp MgF2 = 6.4 x 10-9)
Nuclear Chemistry: The study of reactions that take place in the nuclei of atoms
• In normal chemical reactions, only the electrons are involved.
• In nuclear reactions, only particles in the nucleus are involved.
Radioactive Nuclei: Nuclei that spontaneously decompose
Isotopes:
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Elements with the same atomic number, but different mass number
Elements with an equal numbers of protons, but an unequal numbers of neutrons
All elements on the Periodic Table have at least one radioactive isotope
Radiation: The emission of anything from a source
Nuclear Radiation: The emission of particles & rays from spontaneously decomposing nuclei
Modes of Radioactive Decay:
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Alpha emission
Beta emission
Gamma emission
Radioactive Particles emitted during nuclear Radiation: (including characteristics)
Particle
Alpha ()
Beta ()
Gamma ()
Description
Helium nucleus
electron
electromagnetic
wave
Mass
4 amu
~0 amu
0 amu
Charge
+2
-1
0
Penetrating
Power
Small
Medium
Great
Nuclear
symbol
4
2
0
-1
0
0
Fission: The splitting of a nucleus into smaller nuclei involving the release of energy
Fusion: The combining of smaller nuclei into a larger nucleus involving the release of energy
Transmutation Reactions:
• Nuclear reactions in which one element is changed into another
• Reactions in which the nucleus of an atom is changed in any way
• Both fission & fusion are examples of transmutation rxns
• Can occur through emission of or bombardment by particles
Balancing transmutation Reactions:
 Write the nuclear symbol (that includes mass & charge) of all the isotopes & particles in the rxn.
 The total mass of the products must equal the total mass of the reactants.
 The total charge (or atomic numbers) of the products must equal the total charge of the reactants.
Nuclear Symbols:
Alpha
Beta
4
0

2
Gamma
0

-1
Neutron
1

0
Proton
1
n
0
Electron
0
p
1
e
-1
Balance each of the following transmutation reactions:
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 emission of Pm-142
 bombardment of Th-231
 radiation of Na-23
 emission of U-238 followed by two separate  emissions:
Drill: Name & describe 3 types of nuclear radiation:
Balance each of the following transmutation reactions:
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 bombardment of Th-235 followed by two separate  emission:
 emission of O-18 followed by a  emission:
 absorption by V-45 followed by neutron emission then  emission
neutron bombardment of Ta-182 followed by  emission then  emission
Nuclear Power: Electrical power produced from the energy of nuclear reactions

The energy generated by most nuclear power plants is obtained from the heat generated
during the fission of U-235.
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U-235 is the only fissionable isotope of uranium
0.71 % of uranium is U-235
99.28 % of uranium is U-238
Nuclear Fission Requirements for Power Plants:
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Chain reaction can occur only when it reaches critical mass
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The percentage of U-235 in uranium is too low to form a chain reaction
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To run a power plant, the U-235 needs to be enriched to ~ 2%
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To make a bomb, the U-235 needs to be enriched to > 70%
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To create a chain reaction, the U-235 % must be increased (enriched) greatly
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Ultra-centrifugation
Drill: Predict Products: Neutron absorption by U-238 followed by two separate  emission:
Discuss Nuclear Breeder Reactors:
Decay Rate: The rate at which radioactive nuclei break down
Half-Life: The time it takes for 50 % of the radioactive nuclei to decompose
1st Order Age Dating Formula: age (t) = (ln(Xi / Xf) t 1/2) / 0.693
Problems:
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Calculate the age of a skeleton found with 0.125 % C-14 when atmospheric C-14 = 1.00 %.
t1/2 of C-14 = 5730 yr:
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Calculate the age of a tooth found with 0.00132 % C-14 when atmospheric C-14 = 1.00 %.
t1/2 C-14 = 5730 yrs
Predict the products in each step when Uranium-234 goes through 5 straight emissions.
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Calculate the age of a bone found with 0.000010 % C-14 when atmospheric C-14 = 1.00 %.
t1/2 C-14 = 5730 yrs
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Drill: Predict the products in each step when Boron-12 goes through  bombardment followed by  emission.
Group Work:
Drill: Show neutron bombardment of Ra-223 followed by 3 alpha emissions
Mass-Energy Relations: E = mc2
Nuclear Facts:
 The mass of any nucleus is different than the sum of the masses of its protons & neutrons
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The energy corresponding to the mass difference can be solved using: E = mc2
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Binding Energy:
o The energy that holds a nucleus together corresponds to m of nucleus
Problem: In an atomic bomb, 40.00 kg of U-235 (235.401) is split into Ba-143 (143.223) +
Kr-89 (89.335) + 2 neutrons (1.014). A) Calculate the energy released.
B) Calculate the wavelength of the g ray.
Drill: Calculate the age of a bone found with 0.000010 % C-14 when atmospheric C-14 = 1.00 %.
t1/2 C-14 = 5730 yrs.
Test Review
Know the radioactive particles & their characteristics.
Know how to balance transmutation reactions.
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Show the intermediates and the final isotope of alpha bombardment of Xe-136 followed by
two separate beta emissions.
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Show the intermediates and the final isotope of neutron bombardment of C-13 followed by
one beta emission.
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Show the intermediates and the final isotope of the fusion of Lithium-8 & Helium-4 followed
by beta emission.
Know how to perform age dating: age (t) = (ln(Xi / Xf) t 1/2) / 0.693
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A fossil contained 3.125% of its original carbon-14. Determine its age.
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Calculate the age of a bone found with 0.000010 % C-14 when atmospheric C-14 = 1.00 %.
(t1/2 C-14 = 5730)
(t1/2 for C-14 = 5730 yrs)
Know How to Determine Reactions & Voltages in an Electrolytic Cells:
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2.0 volts are applied to a system through 2 platinum electrodes in an aqueous solution
containing ZnCl2(aq) & CaBr2(aq).
Calculate:
o The reaction occurring at the anode
o The reaction occurring at the, cathode
o The total reaction that occurs
o The voltage required to drive the reaction.
Know how to make electroplating calculations:
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Charge (mass) = current x time
coul = amp x sec
q = It
Saul’s Rule: nFm = MIt
Problems:
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Calculate the mass of Al purified from Al2O3 using a current of 96.5 MA for 5.0 hrs.
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Calculate the time required to plate 1.08 g of silver onto a cathode using a current of 965 mA.