Chapter 18, Problem 27QAP

Interpretation Introduction

(a)

Interpretation:

The balanced nuclear reaction for the decay of iodine-131 should be written.

Concept introduction:

A reaction in which a nucleus of an atom or two nuclei and a subatomic particle collide to form one or more nuclide which is different from the starting nuclide is known as nuclear reaction. Nuclear reactions can be classified as nuclear fission and nuclear fusion.

Interpretation Introduction

(b)

Interpretation:

The activity of 2.50 g sample of iodine-131 in Ci should be determined.

Concept introduction:

Activity is defined as the product of rate constant and number of atoms. It is also defined as the rate of decay or expresses number of atoms decays in unit time.

The mathematical expression is given by:

$\text{A = kN}$

Where, A = activity, k = first order rate constant and N = number of radioactive nuclei.

Activity can be expressed in following units:

1 Bq = 1 atom/s

1 Ci = 3.700 × 10¹⁰ atoms/s

The relation between half-life and first order rate constant is given by:

$\text{k=}\frac{\text{0}\text{.693}}{{\text{t}}_{\text{1/2}}}$

Where, k = first order rate constant and ${\text{t}}_{\text{1/2}}$ = half-life