A pure sample of tritium, ³H, was prepared and sealed in a container for a number of years. Tritium undergoes β decay with a half-life of 12.32 years. How long has the container been sealed if analysis of the contents shows there are 5.25 mol of ³H and 6.35 mol of ³He present? A)2.34 y B)3.38 y C)9.77 y D)14.1 y E)25.6 y

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Quizplus · Accepted Answer

The decay of tritium can be represented by the following equation: ³H → ³He + β- We can use the ratio of the number of moles of helium-3 to the number of moles of tritium to determine how many half-lives have elapsed since the container was sealed: 6.35 mol ³He / 5.25 mol ³H = 1.21 Since tritium has a half-life of 12.32 years, 1.21 half-lives represent a time period of: t = (1.21)(12.32 y) = 14.1 y Therefore, the container has been sealed for 14.1 years.

A Pure Sample of Tritium, 3H, Was Prepared and Sealed

A Pure Sample of Tritium, ³H, Was Prepared and Sealed