Tag Archives: Half-Life

Reactant Half-Life

The concentration of a reactant in a first-order decomposition reaction is decreased to 1/8 of its original value in 100 s. What is the half-life of the reactant?

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Radionuclide Half-Life

What is the half-life of a radionuclide if 1/16 of its initial mass is present after 2 hours?

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[hide-this-part morelink=”Reveal Answer”]

In every half-life, the mass decreases to half its previous value:

1/16 = 1/24

It takes four half-lives to decay down to 1/16 the original mass. Each must be 30 minutes long since the entire process takes two hours.


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