Question

Calculate and compare the energy released by a) fusion of 1.0 kg of hydrogen deep within Sun and b) the fission of 1.0 kg of ²³⁵U in a fission reactor.

Answer 1

Dear Student,

◆ Answer -

• E(H) = 39.14×10^26 MeV
• E(U) = 5.126×10^26 MeV
• E(H)/E(U) = 7.636

● Explaination -

a) No of H-atoms in 1 kg are -

N(H) = 1000/1 × 6.022×10^23

N(H) = 6.022×10^26 atoms

4 H-atoms fuse to give 1 He-atom releasing 26 MeV energy.

Energy released by fusion of 1 kg hydrogen is -

E(H) = Eo × N(H)/4

E(H) = 26 × 6.022×10^26 / 4

E(H) = 39.14×10^26 MeV

b) No of U-atoms in 1 kg are -

N(U) = 1000/235 × 6.022×10^23

N(U) = 2.563×10^24 atoms

During fission of 1 U-atom, 200 MeV energy is released.

Energy released by fusion of 1 kg uranium is -

E(U) = Eo × N(U)

E(U) = 200 × 2.563×10^24

E(U) = 5.126×10^26 MeV

# Comparing energies -

E(H)/E(U) = 39.14×10^26 / 5.126×10^26

E(H)/E(U) = 7.636

Hence, fusion of 1 kg of hydrogen releases 7.6 times energy as that of fission of 1 kg uranium.

Best luck...