Question

a sample of sodium-24 with an activity of 12 mCi is used to study the rate of blood flow in the circulatory system. If sodium-24 has a half-life of 15 h, what is the activity of the sodium after 2.5 days. please show work.

Answer 1

1). half life = ln(2) / lambda

where lambda is the radioactive decay constant

2). A(t) = 12mCi * e ^ - (lambda * t)

where t is time, A(t) is activity as a function of time


15 hr = ln2 / lambda

solve for lambda

convert 2.5 days to hours
Then t = 2.5 days * (24 hrs / day)

Plug these numbers into A(t)