an element has a half-life of 9.8 e3. How long will it take to lose 6% of it potency (94?

Question

need to know how to do this for a test

Answer 1

solve for decay constant (k)
k = (0.693 / t1/2)

plug into 1st order rate equation:
ln[Nt] - ln [No] = -kt

where Nt = amount after time t No = initial amount
Solve for t

ln95 - ln 100 = -kt

You got k and now you can find t!

Good Luck!

Answer 2

Do you have the half life formula? Forget it exactly, but it says that the amount is equal to the initial amount times some exponential or log function that has t for time in it. If you plug in 100 for the intial amount and 94 for the final amount you should be able to solve for t. I think the formula has a natural log in it.