The half-life of Yttrium-91 is 59 days. How much of a 4.11 g sample of Yttrium-91 will remain after 354 days?
回答 (3)
2017-07-29 12:56 am
No. of half-lives = 354/59 = 6
Mass of Yttrium-91 will remain after 354 days
= (4.11 g) × (1/2)⁶
= 0.0642 g
Mass of Yttrium-91 will remain after 354 days
= (4.11 g) × (1/2)⁶
= 0.0642 g
2017-07-29 1:03 am
the general form of the equation you should use... (hint.. memorize it).. is
.. A(t) = A(o) * (1/2)^(t / half life)
where
.. A(t) = amount remaining after time = "t" has elapsed
.. A(o) = initial amount
... ..t = elapsed time
so..
.. A(t) = 4.11g * (1/2)^(354/59) = 0.0642g
.. A(t) = A(o) * (1/2)^(t / half life)
where
.. A(t) = amount remaining after time = "t" has elapsed
.. A(o) = initial amount
... ..t = elapsed time
so..
.. A(t) = 4.11g * (1/2)^(354/59) = 0.0642g
2017-07-29 12:54 am
354 days is 354/59 (ie 4) half lives.
After 354 days, 4.1*(1/2)^4 g remain
4.1/16 = 0.25625 g remains.
After 354 days, 4.1*(1/2)^4 g remain
4.1/16 = 0.25625 g remains.
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