12.4.2 Practice: A Pound of This and a Pound of That
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iammost...@gmail.com
Jan 15, 2013, 12:22:55 AM1/15/13
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12.4.2 Practice: A Pound of This and a Pound of That
Fission
1.Uranium-235 decays naturally, by alpha decay. Write the balanced decay equation below. (5
points)
235/92 U → 231/90 Th + 4/2 He
2.Uranium-235 has a half-life of about 700 million years. If 1 kg of U-235 is put on a shelf in a
laboratory, how much of it will be left after 700 million years? (5 points)
¼ kg
3.Uranium-235 is a popular choice of fuel for nuclear reactors. But U-235 doesn't always fission
the same way. Below are three ways it can split. Complete the nuclear equations so they balance.
(6 points)
56 Be
b)
36 Un
52 Pu
4.Instead of allowing 1 kg of U-235 to decay naturally, imagine it is used as fuel in a nuclear
reactor. It is bombarded with neutrons, causing it all to fission in a matter of days. After 1 kg of
U-235 undergoes fission, the mass of the products is 8.4 x 10-4 kg less than the initial 1 kg. How
much energy was produced by the fission of 1 kg of U-235? (Hint: Use Einstein's equation, E =
mc2, where E is energy in Joules, m is mass in kilograms, and c is the speed of light, 3 x 108 m/
s.) (8 points)
7.56 x 10^13
Fusion
5.The fusion of two hydrogen isotopes is shown below. Complete the nuclear equation so it
balances. (5 points)
2k
6.If 1 kg of fuel is used in the above fusion reaction, the resulting helium has a mass of 0.993 kg.
In other words, 0.007 kg of mass is converted to energy. How much energy is produced by the
fusion of 1 kg of hydrogen? (Hint: Use Einstein's equation, E = mc2, where E is energy in Joules,
m is mass in kilograms, and c is the speed of light, 3 x 108 m/s.) (6 points)
6.3 x 10^14 j
Alternative Energy
7.Hydrogen fuel cells combine hydrogen and oxygen to produce water and energy. Assume 1
kg of fuel is used, and the mass of the water produced is 1.10 x 10-11 kg. How much energy is
produced by this fuel cell? (Hint: Use E = mc2.) (7 points)
16 kwh
Comparison
8.Complete the following table and questions. (8 points)
Reaction
Mass "Lost" Energy Produced
Fission of 1 kg of U-235
½ kg
Fusion of 1 kg of hydrogen
1/3 kg
Fuel cell with 1 kg of hydrogen and oxygen 1/3 kg
75.6 x 10^12 j
6.3 x 10^13 j
5.4 x 10^13 j
Which type of reaction "loses" the most mass?
Fuel Cell
Which type of reaction produces the most energy? Why?
Fission of 1 kg U-235
Fission
1.Uranium-235 decays naturally, by alpha decay. Write the balanced decay equation below. (5
points)
235/92 U → 231/90 Th + 4/2 He
2.Uranium-235 has a half-life of about 700 million years. If 1 kg of U-235 is put on a shelf in a
laboratory, how much of it will be left after 700 million years? (5 points)
¼ kg
3.Uranium-235 is a popular choice of fuel for nuclear reactors. But U-235 doesn't always fission
the same way. Below are three ways it can split. Complete the nuclear equations so they balance.
(6 points)
56 Be
b)
36 Un
52 Pu
4.Instead of allowing 1 kg of U-235 to decay naturally, imagine it is used as fuel in a nuclear
reactor. It is bombarded with neutrons, causing it all to fission in a matter of days. After 1 kg of
U-235 undergoes fission, the mass of the products is 8.4 x 10-4 kg less than the initial 1 kg. How
much energy was produced by the fission of 1 kg of U-235? (Hint: Use Einstein's equation, E =
mc2, where E is energy in Joules, m is mass in kilograms, and c is the speed of light, 3 x 108 m/
s.) (8 points)
7.56 x 10^13
Fusion
5.The fusion of two hydrogen isotopes is shown below. Complete the nuclear equation so it
balances. (5 points)
2k
6.If 1 kg of fuel is used in the above fusion reaction, the resulting helium has a mass of 0.993 kg.
In other words, 0.007 kg of mass is converted to energy. How much energy is produced by the
fusion of 1 kg of hydrogen? (Hint: Use Einstein's equation, E = mc2, where E is energy in Joules,
m is mass in kilograms, and c is the speed of light, 3 x 108 m/s.) (6 points)
6.3 x 10^14 j
Alternative Energy
7.Hydrogen fuel cells combine hydrogen and oxygen to produce water and energy. Assume 1
kg of fuel is used, and the mass of the water produced is 1.10 x 10-11 kg. How much energy is
produced by this fuel cell? (Hint: Use E = mc2.) (7 points)
16 kwh
Comparison
8.Complete the following table and questions. (8 points)
Reaction
Mass "Lost" Energy Produced
Fission of 1 kg of U-235
½ kg
Fusion of 1 kg of hydrogen
1/3 kg
Fuel cell with 1 kg of hydrogen and oxygen 1/3 kg
75.6 x 10^12 j
6.3 x 10^13 j
5.4 x 10^13 j
Which type of reaction "loses" the most mass?
Fuel Cell
Which type of reaction produces the most energy? Why?
Fission of 1 kg U-235
jacobr...@gmail.com
Jun 15, 2017, 12:28:43 PM6/15/17
to PLC Physical Science, iammost...@gmail.com
teacher
Sep 27, 2019, 9:13:59 AM9/27/19
to PLC Physical Science
You would be the best if you knew what you were talking about...
abby kara
Nov 9, 2020, 12:37:35 AM11/9/20
to PLC Physical Science
is this all correct??
John Timber
Nov 9, 2020, 11:55:30 AM11/9/20
to plc-physic...@googlegroups.com
Sorry, I don't remember turning this in? You might have the wrong person because I am in Chemistry.
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abby kara
Nov 9, 2020, 7:13:27 PM11/9/20
to PLC Physical Science
is this all correct?
Alex Strazzullo
Dec 15, 2020, 2:18:01 PM12/15/20
to PLC Physical Science
was it right?
Idunno452
Dec 15, 2020, 4:56:50 PM12/15/20
to PLC Physical Science
Which type of reaction "loses" the most mass?
Fuel Cell
Fuel Cell
This answer is definitely wrong
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