CHEM1101 Sample Quiz Help! (1 Viewer)

[nml10]

How do you solve "What is the specific activity (in Ci g^-1) of the nuclide '90 35 Br' whose half life is 1.6 seconds?" ?

 

[funnytomato]

assuming you know how to derive : t(1/2)= ln(2)/lambda , from the N(t)=N0 * exp(-lambda*t) and N(t(1/2))= half of N0

and the rate of dacay(disintegrations per second) is proportional to the number of nuclei, by computing dN/dt
i.e. Activity= lambda*N

so you can get lambda from the 1st eqn,
then find how many moles in 1g of Br 90 35 (1g/molar mass), muptiply by avacado's number to get the number of atoms
And use the 2nd equation to find disintegrations/second, and convert to the right unit

 

[funnytomato]

^this is how I'd do it, and it may not be totally correct