A radioactive element has a half-life of 3.5 million years. If 100 grams were stored today, how much would be left in 7 million years.
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A radioactive element has a half-life of 3.5 million years. If 100 grams were stored today, how much would be left in 7 million years.
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HALF LIFE
A radioactive element has a half-life of 3.5 million years. If 100 grams were stored today, how much would be left in 7 million years?
Given
Find first the rate constant
k = ln 2 / t½
k = 0.6931 / 3,500,000
k = 1.98039 x 10⁻⁷
Compute the final amount
Af = A₀e⁻ᵏᵗ
Af = 100e⁽⁻¹.⁹⁸⁰²³ ˣ ¹⁰^⁻⁷⁾⁽⁷⁰⁰⁰⁰⁰⁰⁾
Af ≈ 25 grams
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