   Chapter 10, Problem 46P ### University Physics Volume 3

17th Edition
William Moebs + 1 other
ISBN: 9781938168185

#### Solutions ### University Physics Volume 3

17th Edition
William Moebs + 1 other
ISBN: 9781938168185
Textbook Problem

# 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? (b) What is its activity 5.00 y after manufacture?

To determine

(a)

The mass of the tritium.

Explanation

Formula used:

The expression to calculate the number of atoms is givenby

N=Rt1/20.693

The expression to calculate the mass is givenby

m=N×M6.02×1023

Here, m is the mass, N is number of atoms and M is the molar mass.

Calculation:

The half-life of tritium is 12.33years.

The number of atoms is calculated as follows:

N=Rt 1/2 0.693=( 15.0Ci× 1Bq 2.70× 10 11 Ci )( 12.33years× 365days 1year × 24hr 1day × 3600s 1hr )0

To determine

(b)

The activity of tritium after the given years of manufacture.

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