Physics
DrucillaSpohr
2016-04-27 11:23:57
The half-life for the radioactive decay of ce?141 is 32.5 days. if a sample has an activity of 3.1 ?ci after 97.5 d have elapsed, what was the initial activity, in microcuries, of the sample? express your answer using two significant figures.
ANSWERS
MireilleKanwar
2016-04-27 15:35:53

Assuming that the radioactive decay of Ce is a 1st order reaction, we can use the following formula to look for the rate constant k.t1/2 = ln 2 / k32.5 = ln 2 / kk = 0.021 day^-1 The integrated rate law for a 1st order reaction is:ln A = -k t + ln AiWhere,A = final activity = 3.1 ciAi = initial activityt = time that elapsed = 97.5 dSubstituting the given values to the equation:ln 3.1 = -0.021 * 97.5 + ln Ailn Ai = 3.18 Ai = 24.02 ci        (ANSWER)

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