Chapter 20, Problem 19E

(a)

Interpretation Introduction

Interpretation : Radioactive copper-64 decays with a half-life of 12.8 days. Then the value of k in s-1 is to be determined.

Concept Introduction : The time required to disintegrate exactly half of the radioactive substance is called half-life period.

(b)

Interpretation Introduction

Interpretation: Asample having 28.0mg ⁶⁴Cu then decay events produced in first second is to be calculated. Considering the atomic mass of is ⁶⁴Cu 64.0 u

Concept Introduction:Spontaneous breakdown of an atomic nucleus and results in release of energy from nucleus is called radioactive decay.

(c)

Interpretation Introduction

Interpretation: The time required to decrease the radioactivity below 25% of the initial measured value needs to be determined.

Concept Introduction : The rate law equation for first order reaction is as follows:

  $\text{ln}\left(\frac{\text{C}}{{\text{C}}_{\text{0}}}\right)\text{=}\text{-kt}$

Where;

C0 = initial radioactivity at t= 0

C = radioactivity at time t

k = rate constant

t = time