Part C Americium-241 is used in some smoke detectors. It is an alpha emitter wit

Question

Part C

Americium-241 is used in some smoke detectors. It is an alpha emitter with a half-life of 432 years. How long will it take in years for 44.0 % of an Am-241 sample to decay?

Express your answer with the appropriate units.

Part D

A fossil was analyzed and determined to have a carbon-14 level that is 60 % that of living organisms. The half-life of C-14 is 5730 years. How old is the fossil?

Express your answer with the appropriate units.

t=________________________

Explanation / Answer

t1/2 = 0.693/k = 432 years

k = 1.6045x10-3 years-1

k = 1/t {ln[A0]/[A]}

t = 1/k {ln[A0]/[A]}

[A]= 100% - 44% = 56%

ln(100 / 56) = 1.6045x10-3 x t

t = 361 years

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