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burritomadness
10.12.2019 •
Chemistry
Radium-221 has a half-life of 30 sec. how long will it take for 96% of a sample to decay?
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Ответ:
A = Ao e^-kt
where A is the amount left at t years, Ao is the initial concentration, and k is a constant.
From the half-life data, we can calculate for k.
1/2(Ao) = Ao e^-k(30)
k = 0.023
0.04Ao = Ao e^0.023(t)
t = 140 sec
Ответ:
C
Explanation:
Breaking bonds always requires energy. The reactants are always on the left side so you are trying to breaks the bonds of NaOH and HCl.