Question

1. The radioactive source you will be working with in this lab is Cs-137. Look up the half-life of this material and report the value in units of seconds. 2. The relationship between decay constant (l) and half-life is:

Answer 1

The question is incomplete, here is the complete question:

1. The radioactive source you will be working with in this lab is Cs-137. Look up the half-life of this material and report the value in units of seconds.

2. The relationship between decay constant (l) and half-life is:

$t_{1/2}=\frac{\ln 2}{k}$

For Cs-137, what is the value of 'k' in $s^{-1}$

Answer:

For 1: The half life for Cs-137 isotope is $9.51\times 10^8s$

For 2: The rate constant of Cs-137 isotope is $7.29\times 10^{-10}s^{-1}$

Explanation:

• For 1:

Half life is defined as the time taken for half of the reaction to complete. This is also defined as the time in which the concentration of a reactant is reduced to half of its original value.

The half life for Cs-137 isotope is $9.51\times 10^8s$

• For 2:

The relationship between decay constant (l) and half-life is: given by the equation:

$t_{1/2}=\frac{\ln 2}{k}$

where,

$t_{1/2}$ = half life of Cs-137 isotope = $9.51\times 10^8s$

k = rate constant

Putting values in above equation, we get:

$9.51\times 10^8s=\frac{\ln 2}{k}\\\\k=\frac{\ln 2}{9.51\times 10^8}=7.29\times 10^{-10}s^{-1}$

Hence, the rate constant of Cs-137 isotope is $7.29\times 10^{-10}s^{-1}$