The half-life of Palladium-100 is 4 days.

Question

The half-life of Palladium-100 is 4 days. After 16 days a sample of Palladium-100 has been reduced to a mass of 1 mg.

What was the initial mass (in mg) of the sample?   

What is the mass 5 weeks after the start?   

Answer 1

The half-life formula: A = Ao*2^(-t/h)

Where

A = resulting amt after t time

Ao = initial amt

t = time of decay

h = half-life of substance

Find the initial amt

Ao*2^(-16/4) = 1

Ao*2^-4 = 1

0.0625*Ao = 1

Ao = 1 / 0.0625

Ao = 16 mg is the initial amt

:

Find the amt after 5*7 = 35 days

A = 16*2^(-35/4)

Enter above into a calc

A = 0.0371 mg after 5 weeks