Question

The β− particles emitted in the decay of ³H (tritium) interact with matter to create light in a glow-in-the-dark exit sign. At the time of manufacture, such a sign contains 15.0 Ci of ³H. (a) What is the mass of the tritium?

(a) 0.75 g
(b) 1.5 g
(c) 2.25 g
(d) 3.0 g

Answer 1

The mass of tritium in a sign with 15.0 Ci at manufacture cannot be determined with the information provided. The activity of tritium will decrease over time, and after five years it will be less than the original activity due to its half-life of 12.32 years.

Step-by-step explanation:

The student has asked about the mass of tritium in a glow-in-the-dark exit sign and the activity of this tritium sample after five years.

The β− particles emitted in the decay of ³H (tritium) interact with matter to generate light. Knowing that the sign contains 15.0 Ci of tritium at the time of manufacture and that the atomic mass of tritium is 3.016 amu, we can calculate its mass. However, more information such as the specific activity of tritium is needed to accurately answer this question.

To find the activity after five years, we would utilize the half-life of the tritium and apply the decay formula. However, the half-life of tritium at 12.32 years indicates that after 5 years, there will be less than 15.0 Ci due to the natural decay process.