 |
||||
    |
||||
Lead - 210 |
||||
|
The half-life of Pb 210 is 20 years. Find the initial number of disintegrations per second for 1.0g of this isotope of lead. 210g lead contains NA (6.02 x 1023) atoms therefore 1 g lead contains 6.02 x 1023/210 atoms (LEAVE IT IN THIS FORM… IT IS NOT A GOOD IDEA TO KEEP ON WORKING OUT SUBSTAGES) N0 = 6.02 x 1023/210 dN/dt = ? half life = 20 years = 20 x 365.25 days = 20 x 365.25 x 24 hours = 20 x 365.25 x 24 x 60 hours = 20 x 365.25 x 24 x 60 x 60 seconds = 6.31 x 108 seconds l = - ln2/half life = - 0.693/(6.31 x 108)
= - (- 0.693 /(6.31 x 108)) x (6.02 x 1023/210) = (0.693 x 6.02 x 1023 )/ (210 x 6.31 x 108) = 3.1 x 1012 s-1 |
||||
 |
 |
|||
