If 75.0 mg of potassium-42 was administered to a patient at 10 AM on Monday,how many mg will remain at 10 AM on Thursday of that same week? The half life of K-42 is 12 hours.

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Quizplus · Accepted Answer

From Monday 10 AM to Thursday 10 AM is 72 hours. The half-life of K-42 is 12 hours, so in 72 hours, it goes through 6 half-lives (72/12 = 6). Starting with 75.0 mg, after each half-life, the amount remaining is halved: 75.0 -> 37.5 -> 18.75 -> 9.375 -> 4.6875 -> 2.34375 -> 1.171875. So, after 6 half-lives, 1.17 mg will remain.

If 750 Mg of Potassium-42 Was Administered to a Patient at at 10