SOLUTION: The mass m(t) remaining after t days from a 25-g sample of thorium-234 is given by
m(t)=25e^(-0.0277)t
a) How much of the sample will remain after 70 days? Round the answer to
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Question 691570: The mass m(t) remaining after t days from a 25-g sample of thorium-234 is given by
m(t)=25e^(-0.0277)t
a) How much of the sample will remain after 70 days? Round the answer to the nearest integer. (Answer should be in terms of grams)
b) After how long will only 10g of the sample remain? Round the answer to the nearest integer. (Answer should be in terms of days)
c) Find the half-life of thorium-234. Round the answer to the nearest integer. (Answer should be in terms of days)
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
The mass m(t) remaining after t days from a 25-g sample of thorium-234 is given by
m(t)=25e^(-0.0277)t
a) How much of the sample will remain after 70 days? Round the answer to the nearest integer. (Answer should be in terms of grams)
m(70) = 25*e^(-0.0277*70) = 3.5962 grams
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b) After how long will only 10g of the sample remain? Round the answer to the nearest integer. (Answer should be in terms of days)
25*e^(-0.0277t) = 10
e^(-0.0277t) = 2/5
-0.0277t = ln(0.4)
t = 33.079 days
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c) Find the half-life of thorium-234. Round the answer to the nearest integer. (Answer should be in terms of days)
e^(-0.0277t) = 1/2
-0.0277t = ln(.5)
t = 25 days when rounded down
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Cheers,
Stan H.
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