Question-2
Tritium ( H3 ) decays by negative beta decay with a half-life of 12.33 years. The atomic weight of H3 is 3.016. What is the mass in grams of 1 mCi of tritium ? |
| Solution - 2 |
| Activity = α = 1 mCi = 3.7 1010 x 10-3 = 3.7 x 107 s-1
= λN |
T1/2 |
= 12.33 years
|
λ |
= 0.693/T1/2 |
|
=0.693/(12.33 x 365.25 x 24 x 3600) |
| |
= 1.781 x 10-9 s-1
|
| |
∴ N= 3.7 x 107/1.781 x 10-9 |
| |
= 2.08 x 1016 nuclei |
Mass of Tritium Atom |
= 3.016/6.023 x 1023 |
|
|
| |
= 5.007 x 10-24 g
|
|
|
Hence total mass |
=5.007 x 10-24 x 2.08 x 1016 |
|
| |
= 1.040 x 10-7 g |
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