# Difference between revisions of "Solutions 4"

1:
Mass excess is given by deltaM(Z,A) = M(Z,A)-A. The masses can therefore be found with M(Z,A) = delta M (Z,A ) + A by using 1 u = 931.5 MeV we get:

• M(n) = 1.008665 u
• M(1H) = 1.007825 u
• M(4He) = 4.002603 u
• M(56Fe) = 55.934938 u
• M(142Ce) = 141.909244 u
• M(238U) = 238.050788 u
1. The most stable nuclei is 56Fe. It has the highest binding energy compared to the number of nucleons.
2. 1.00 kg 2H is 496.5 mol by fusion 248,2 mol 4He is created which is 993.6 g. The difference in mass is equal to the energy 1000 g-993.6 g = 6.36 g. The energy is then 5.7 1014 J, 3.56  1027 MeV or 1.59 108 kWh.
3. 1.00 kg 233U fission to 92Rb, 138Cs and three neutrons. The mass difference is 0.785 g. Which gives 7,11013 J, 4.40 1026 MeV or 1.96107 kWh.
4. The energy from the fission is distributed in different ways: most of it goes to the kinetic energy of for the fission products. Other parts goes to the kinetic energy of the neutrinos and the neutrons, and some of it goes to “prompt” gamma-rays and beta/gamma rays from the fission products.

2:

binding energy B per nucleon:

It is 0.00868 u per nucleon

and 8.26 MeV per nucleon

3:

times bigger binding energy for the nucleus.

4:

1. M(n) = 939.6 MeV.
2. M(e) = 0.511 MeV.
3. M("u") = 931.5 MeV.

5:

1. 8.55 MeV/nucleon.
2. 8.79 MeV/nucleon.
3. 7.86 MeV/nucleon.

6: The energy

M(235U) - (M(131Xe + M(101Ru) + 3M(n)) =

(ΔM(235U) + 235) - (Δ(131Xe) + 131) - (ΔM(101Ru) + 101) - 3(ΔM(m) + 1)

= ΔM(235U) - ΔM(131Xe) - ΔM(101Ru) - 3ΔM(n)

=40.916 + 88.421 + 87.952 - 3 8.071 = 193.08 Mev

7:

Energy usage per 10 km:

1 L = 700 g. Mm(C8H18) = 114 g/mol, this means that 700 g is 6.14 mol.

6.14 mol 5500 kJ/mol = 33771.93 kJ, with a fuel efficiency of 18% the usage per 10 km is 6078.94 kJ/(10 km).

1 g 235U=4.2510-3 mol = 2.561021 atoms.

If all of the atoms fission and assuming 100% efficiency this will give 5.121029 eV = 8.22107kJ. Which will last for 135190 km.

8:

. Which means that for each H2O molecule it is generated 237kJ/NA = 2.456*10^6MeV. Comparing to 0.0303 u = 23.2 MeV realesed by fusion to helium. We see that the nuclear reactions functions on a scale 10^6 times bigger than chemical.