Post a New Question

calc

posted by .

The half-life of polonium is 139 days, but your sample will not be useful to you after 95 % of the
radioactive nuclei present on the day the sample arrives has disintegrated. For about how many days
after the sample arrives will you be able to use the polonium?

you want to know when you have 5% left.

Let P = c(2)^(-t/13), where c is the amount you started with, and t is the number of days.

so we want .05c=c(2)^(-t/139)

I used logs to solve and got t = 600 days

  • calc -

    t=139ln(.05)/(ln(1/2))

    t=139ln(.05)/(ln(1)-ln(2))

    t=139ln(.05)/(0-ln(2))

    t=139ln(.05)/(-ln(2))=600.7480052=600 days

    t=(half life* ln(percent of sample left))/(ln(1/2))

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. physics-Radioactivity

    1) The number of radioactive nuclei in a particular sample decreases over a period of 15 days to one-seventeenth the original number. What is the half-life (in days) of these nuclei?
  2. physics

    Suppose 32000 radioactive nuclei are in a sample. About how many remain after two days if the half-life is 22 hrs?
  3. physics

    The half life of a radioactive sample is 6.93 days.after how many days will only one -tenth of the sample be left behind?
  4. Science math

    Suppose a laboratory has a 38 g sample of polonium-210. The half-life of polonium-210 is about 138 days. How many half-lives of polonium-210 occur in 1104 days?
  5. science

    Suppose a laboratory has a 31 g sample of polonium-210. The half-life of polonium-210 is about 138 days. How many half-lives of polonium-210 occur in 966 days?
  6. sciencemath

    Suppose a laboratory has a 31 g sample of polonium-210. The half-life of polonium-210 is about 138 days. How many half-lives of polonium-210 occur in 966 days?
  7. Pre-Calc

    A radioactive isotope has a half life of 8.1 days. If the sample starts with 25 grams, how much will there be after 90 days?
  8. physics

    The number of radioactive nuclei present at the start of an experiment is 3.27 x 1015. The number present twenty days later is 7.66 x 1014. What is the half-life (in days) of the nuclei?
  9. pre calc

    You have a sample of a certain radioactive substance. After two days, thirty percent of the sample has decayed. What is the half-life of the material and how much will have decayed after a week?
  10. pre calc

    You have a sample of a certain radioactive substance. After two days, thirty percent of the sample has decayed. What is the half-life of the material and how much will have decayed after a week?

More Similar Questions

Post a New Question