[gsunshin]

Hello,

I am working on a problem and have tried a plehtora of different ways to get the answer but was unsuccessful.

Plutonium-239 decays by alpha emission. The isotope's half-life is 2.4 x 10^4 years. How many alpha particles are emitted per second by 1.0x10^-4 moles Plutonium-239?

I know the answer is (5.5x10^7 alpha particles / s) but can not get it to match. Thank you for any help.

[gkasparis]

well....i'm coming out with a different answer but close so:

1 year=365 days=...=3153600 seconds
the t_1/2=2.4*10⁴years    convert that to seconds t_1/2=7.56864*10¹¹seconds
 since you dont have the actual equation of the decay let assume that 1mol of Pu gives you 1mol of He and 1mol of the other substance X
at the half-life you will have 0.5mol of Pu, 0.5 mol of He and 0.5mol of X, similarly 0,0001mol of Pu will give you 0.0001 mol He. multiply that with the avogadro number. you will end up with 6.02214*10¹⁹ helium atoms at half-life (at 7.56864*10¹¹ seconds). to get the He atoms per second divide it by the half life in seconds and i get almost 8*10⁷

although not quite sure since you give a different answer