ln(No/N) = kt
No = 40g
N = 5
k = ?
t = 90 min
Solve for k
Then k = 0.693/t1/2
Solve for half life in minutes.
Another way to do it is
(40/2*x) = 5
solve for x
Then 90 minutes/x = time for 1 half life.
You should get the same answer both ways.
If a 40 gram sample of radioactive isotope was present at 4pm, but a 5 gram sample remained at 4:30 pm, what is the half-life in minutes?
1 answer
1 answer