# calc

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

1. 👍 0
2. 👎 0
3. 👁 344
1. 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))

1. 👍 0
2. 👎 0
posted by Billie

## Similar Questions

1. ### 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? How much polonium is in the sample 966 days later?

asked by Anonymous on March 19, 2013
2. ### 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? How much polonium is in the sample 966 days later?

asked by Anonymous on March 19, 2013
3. ### 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? How much polonium is in the sample 1104 days later?

asked by Joshua on January 7, 2013
4. ### integrated math

Suppose a laboratory has a 26 g sample of polonium-210. The half-life of polonium-210 is about 138 days.?

asked by sara on January 15, 2013
5. ### algebra

Consider that the half-life of Polonium-210 is 140 days.What approximate daily percentage of decay does Polonium-210 demonstrate?% (Round to two decimals.)(Hint: use the Rule of 70 backwards by dividing by the half-life period

asked by Tristan on October 1, 2015
6. ### physics

How long will it take a sample of polonium-210 with a half-life of 140 days to decay to one-sixty-fourth of its original strength?

asked by katie on January 15, 2014
7. ### chemisty

What is the half-life of polonium-218 if 5.37 minutes are required for the activity of a sample of polonium-218 to fall to 29.5 percent of its original value?

asked by chan on September 10, 2017
8. ### Chemistry

Static charge can interfere with the production of plastic products by attracting dust and dirt. to reduce it, manufacturers expose the area to polonium-210, which has a half-life of 138 days. How much of a 25.0-g sample will

asked by S on July 21, 2016
9. ### chemistry

the half-life of polonium-218 is 3.0 minutes. what percentage of the original sample remains after 4 half-lives?

asked by melissa on December 10, 2008
10. ### Math

How long will it take for a 1 g sample of Polonium 210 to lose all but 1/28 of its radioactivity if the half-life is 140 d?

asked by Kate on August 1, 2011

More Similar Questions