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Please Help With Chem Problem?
A woman drinks some contaminated milk and ingests 0.0645 g of 90Sr, which is taken up by bones and teeth and not eliminated?
a) How much 90Sr (t1/2 = 29 yr) is present in her body after 19 yr?
(b) How long will it take for 94.3% of the 90Sr to decay?
1 Answer
- Simonizer1218Lv 75 years agoFavorite Answer
For first order decay, % remaining = 0.5^n where n = number of 1/2 lives
19 yr/29 yr = 0.66 half lives
% remaining = 0.5^0.66 = 0.633
amount remaining = 0.633 x 0.0645 g = 0.0408 g
for 94.3% to decay, the % remaining will be 5.7 or fraction remaining will be 0.057
0.057 = 0.5^n and n = 4.13 half lives
4.13 x 29 yr = 118.9 yrs
