| SCI 270: On Nuclear Technology Practice Problems |
Answers are given for your reference only. Please do your part of
the learning, because no one else will be able to do that for you.
Your skills of problem solving are tested and useful in the future. Answers are useless. Acquiring skills and abilities are the goals of learning, marks indications of your performances on these tasks.
Calculate the amount of energy Q in MeV (actually MeV/molecule) for each 4He atom formed. Also evaluate the energy Q in J per mole of 4He gas formed.
If all particles are counted, we have the balanced reaction equation:
|Relative energy content|
The difference between the second and the third is the binding energy of deuterium.
The conservation of mass-and-energy is well illustrated in these calculations. On the other hand, the calculation is based on the conservation of mass-and-energy.
Each D, T fusion reaction releases 17.6 MeV
(1.6021E-13 J/MeV) = 2.819E-12 J/(D, T, or He)
In order to produce 1016 J, we carry out the calculation this way
Since we are calculating the mass of D2, a mass of 2 rather than the precise rest mass of D is adequate. Why 2 g of D2 rather than 4 g of D2 is used?
1 mol C3H8 (3*12.011+8*1.008) g C3H8 10E16 J ---------- ---------------------- 2202 J 1 mol C3H8 = 2.08E14 g = 2.1E11 kg of propane.
Actually the heat of combustion for propane is 2202 kJ/mole. There are certain conditions to be met for this value, and for more accurate estimates, the conditions must be specified. In this simple exercise, you are only interested in developing a method to estimate. Thus the weight of propane is 2.1E8 kg (200 milion kg) as opposed to a total mass of 29 kg of T and D. Of course, a lot of physics, chemistry, and engineering is involved in the making of H-bomb.
The electrolysis did show a large amount of energy released. The possible fusion reactions are those given in the text, namely,
The questions should provoke you to think deeper when you have just learned of a new discovery. Only when all your questions are satisfactory answered, you can accept the results.