Question

If 3.420g of ^226 Ra (t 1/2= 1620 yrs) is separated from its decay products and placed in a sealed 1L vessel, what is the partial pressure (in torr) of helium after 45 days if the vessel is at 0 degrees C? The half life of Rn is = 3.82 days

Do Not Assume that ^218 Po is stable. Consult a nuclear wallet card to determine what it will decay to, and what this daughter will decay to, etc. This decay chain extends to ^210 Pb which has a long half life compared to measurement time.

Hint: despite the long decay chain, you will only need to consider three isotopes (apart from helium) in your calculation, (why? Consider your half lives!)

The gas constant R= 62.363 L*torr*K^-1 mol^-1