How long will it take for 52.0% of a 0.00970 mg sample of radioactive phosphorus-32 to decay?

Question

The half-life of phosphorus-32 is 14.30 days, so give your answer in days.

Answer 1

If 52% is decayed, then you will have 48.0% of the original amount of sample left. So find out how many mg it is by multiplying 0.00970 mg by .480. It is 0.00466 mg. To find out how many half-lives it takes for this to occur, set up the equation 0.00466 = 0.00970/2^x. x is 1.06 half-lives, so multiply that by 14.30 days and you will get the answer. It is 15.16 days.

Answer 2

15.145 days.