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If 1.00×10−12molof 135Csemits1.39×105β− particles in1.00yr , what is the decay constant?

Short Answer

Expert verified

The decay constant is2.31×107yr−1 .

Step by step solution

01

Definition of decay constant

The size of a population of radioactive atoms and the pace at which the population diminishes due to radioactive decay are proportionate.

02

Calculate the decay constant

The initial amount of 135Cis:

N0=1.00×10−12mol⋅6.022×1023atoms1mol=6.022×1011atoms.

After t=1.00yr, 1.39×105 â¶Ä‰â¶Ä‰â¶Ä‰135Csatoms decayed.

Therefore,

Nt=N0−1.39×105=6.023×1011atoms−1.39×105atoms=6.02199861×1011atoms.

Now, let us calculate the decay constant

role="math" localid="1663381581251" lnNtN0=−ktk=−lnNtN0t=−ln6.02199861×1011atoms6.022×1011atoms1yr=2.31×107yr−1.

Therefore, the computed value is 2.31×107yr−1.

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