3.25 mole of a radioactive isotope with a half-life of 18.2 hours sits on a countertop for 2.7 days exactly.How much of the isotope is left?

Question

Quizplus · Accepted Answer

First, convert 2.7 days to hours: 2.7 days * 24 hours/day = 64.8 hours. Then, calculate the number of half-lives: 64.8 hours / 18.2 hours/half-life = 3.56 half-lives. The amount of isotope left after 3.56 half-lives is found by (1/2)^3.56 * 3.25 moles ≈ 0.28 mole.

325 Mole of a Radioactive Isotope with a Half-Life of 18.2