1.) The mass of Cobalt-60 in a sample is found to have decreased from 5.4 grams to 1.20 grams. In a period of 10.6 years, from their formation, calculate the half-life of Cobalt-60.
2.) Manganese-56 has a half-life of 2.6 hours. Assuming you start with a sample of 10 grams of Manganese-56, how much will remain after 24.3 hours?
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2.) Manganese-56 has a half-life of 2.6 hours. Assuming you start with a sample of 10 grams of Manganese-56, how much will remain after 24.3 hours?
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Half life = 0.693 / k ..... where k is the decay constant.
ln A = -kt + ln Ao
ln (A/Ao) = -kt
k = -ln(A/Ao)/t
Half-life = 0.693 / -ln(A/Ao)/t
Half life = 0.693 / (-ln(1.2/5.4)/10.6yr)
Half=life = 4.88 yr
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k = 0.693 / t(1/2) = 0.693 / 2.6 hr = 0.2665 1/hr
A = Ao e^-kt
A = 10g x e^-(0.2665 x 23.3) = 0.0201g
ln A = -kt + ln Ao
ln (A/Ao) = -kt
k = -ln(A/Ao)/t
Half-life = 0.693 / -ln(A/Ao)/t
Half life = 0.693 / (-ln(1.2/5.4)/10.6yr)
Half=life = 4.88 yr
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k = 0.693 / t(1/2) = 0.693 / 2.6 hr = 0.2665 1/hr
A = Ao e^-kt
A = 10g x e^-(0.2665 x 23.3) = 0.0201g