Consider the decay 92 U 143 90 Th 141 + 2 He 2 . Part (a) What energy, in megael
ID: 1499243 • Letter: C
Question
Consider the decay 92U143 90Th141+2He2.
Part (a) What energy, in megaelectron volts, is released in this decay? The mass of the daughter nuclide is 231.036298 u.
Hints:
-If the rest energy on the left side of the decay process is greater than on the right side, some energy must have been released.
-You will have to look up the rest energies of 235U and 4He.
For part a I've gotten 1855 and 5.963 and both were wrong.
Part (b) Assuming the residual nucleus is formed in its ground state, how much of the released energy, in megaelectron volts, goes to the particle? Assume the uranium nucleus starts at rest.
Hints:
-You may use non-relativistic energy and momentum considerations for this process.
-Notice that kinetic energy is not conserved in this process - only momentum is.
-Where does the extra energy from part (a) go?
for part b I've gotten 1855, and 5.86 and both were wrong.
Explanation / Answer
a) mass lost (del(m)) = mass of U235- mass of Th - mass of He
= 235.043929- 231.036298- 4.002604
= 5.027 * 10^-3 u
Energy released = del(m) * C^2 ----------( converting mass into its energy equivalent )
= 5.027 * 10^-3 * 931.5 MeV ( because 1 amu = 931.5 MeV)
E = 4.682 MeV
B) the energy relesed will be divided between alpha particle and heavely recoiling daughter nuclei.
if uranium is in rest, energy goes to alpha particle will be in the form of kinetic energy as only momentum is conserved not the kinetic energy
energy (goes to alpha particle) = (231.036298/235.043929) * energy released during alpha decay
= 0.9829 * 4.682
= 4.6019 MeV