Nuclear Physics: energy released in alpha particle...?

Question

Find the energy re;eased in the alpha decay of 238/92 U (238 being the top number...). The following mass value will be useful: 234/90 Th has a mass of 234.043583 u.

HELP!! how do i solve this problem?

Answer 1

238/92 U --> 4/2 alpha + 234/90 Th

do the same as i have showed you in the other 2 questions!!!!

by finding out energy for them all using e=mc^2 (as you know there masses--> convert them to Kg first!)

energy of  alpha + its k energy = energy of U - energy of Th

its k.e = energy of U - take energy of Th - energy of alpha

this is not the energy they have. its all to do with energy-mass conservation!!! but will give u the right answer

Answer 2

difficult, you have to know the chemical equation of the decay and each component atomic weight. in my file i have a Pu239 decay chemical equation

Pu239 ---> He4 + U235

239.05218 amu ---> 4.0026033 amu + 235.04394 amu

239.05218 amu ---> 239.0465433 amu

mass loss = 0.0056367 amu

according to einstein this mass is converted to energy by E=mc^2

or simply

1 amu loss = 1.494E -10 J = 931.478 MeV

so, in example above

E = 0.0056367 * 931.478 MeV

if you prefer to calculate using E = mc^2, make sure you use the proper units

1 amu = 1.6606E - 27 kg

E= energy in joules

m = mass in kg in this case 1.6606E - 27 kg

c = speed of light 299 792 458 m/s

E = mc^2 = 1.4924E - 10 J for 1 amu mass loss

probably your decay equation is

U238 ---> Th234 + alpha He4

no neutron is involved unless an explosion happened