Question

Part A

Convert the 200 MeV per nucleus energy that is released by 235U fission to units of joules per kilogram.

Express your answer using two significant figures.

Part B

By comparison, the energy release by burning coal is 3.3×107J/kg. Find the ratio of the energy released by 235U fission to the energy from coal per unit mass .

Express your answer using two significant figures.

Answer 1

200MeV per nucleus

The atomic mass of U-235 is 235.0439

so, no. of moles in 1 kg= 4.255 moles

in 4.255 moles, no. of atoms = 4.255 * 6.022×10²³ atoms= 2.562x10²⁴ atoms

so total energy per kg = 200MeV/atom* 2.562x10²⁴ atoms= 5.1247 x10²⁶ MeV

1 eV= 1.60218e^-19J

so joules per kilogram.= 5.1247 x10²⁶ * 10⁶ * 1.60x10^-19J= 8.1995 x10¹³ J

PART B

he ratio of the energy released by 235U fission to the energy from coal per unit mass .

uranium /coal = 8.1995 x10¹³ J / 3.3×10⁷J/kg = 2484696.97