Question

the half life of phosphorous-32 is 14.3 days. How many grams will remain after 23 days if 9.00 grams of this isotope were present originally?

Answer 1

since it's a 1st order process you can use the integrated rate law:

\(ln[A]=-kt+[A]_o\)

\([A]_o\)=initial amount
\([A]\)=amount after time, t, elapsed
k=decay constant
t=time

you can find k with: \(t_{1/2}=\dfrac{ln(2)}{k}\)