# Ap chemistry

a sample of radioactive iodine (half life=3 days) originally weighed 10 g, but now weighs 0.625 g. How old is the sample?

1. 👍 0
2. 👎 0
3. 👁 174
1. 0.625 = 10 (1/2)^(t / 3)

log(0.625 / 10) = (t / 3) log(1/2)

or ... 10 , 5 , 5/2 , 5/4 , 5/8

1. 👍 0
2. 👎 0
2. 0.625 = 10 * (1/2)^n
0.00625 = .5^n
log 0.00625 = n log 0.5
n = log 0.00625 / log 0.5
n is the number of 3 day periods
time in hours = n * 3 * 24

1. 👍 0
2. 👎 0

## Similar Questions

1. ### Chemistry

The iodine-131 nuclide has a half-life of 8 days. If you originally have 625-g sample, how many grams will you have after 2 months(approximately 64 days)?

2. ### science

The iodine-131 nuclide has a half-life of 8.0 days. If you originally have a 257 g sample, after 48 days how much will you have?

asked by emma on May 5, 2017

There are 3.29g of iodine -126 remaining in a smple originally containing 26.3 g of Iodine - 126 the half life of Iodine - 126 is 13 days. How old is the sample? At study hall test is after lunch and cant figure out htese 2 on my

asked by sam on February 8, 2008

There are 3.29g of Iodine 126 remaining in a smaple originally containing 26.3 g of iodine 126 the half life of iodine 126 is 13 days. How old is the sample?

asked by sam on February 7, 2008
5. ### Math

Please show me how to solve: Doctors can use radioactive iodine to treat some forms of cancer. The half-life of iodine - 131 is 8 days. A patient receives a treatment of 12 millicuries of iodine - 131. (A mullicurie is a unit of

asked by Jane on January 22, 2012
1. ### Chemistry

2. The half-life of a radioactive element is important when considering its application in medicine. For example, iodine-131 is often used in the imaging of the thyroid. The reason is that iodine is readily absorbed by the thyroid

asked by Mickey on September 28, 2014

Iodine-131 is a radioactive isotope. After 8.00 days, 50.2% of the sample remains. What is the half life of 131-I?

asked by Jessica on September 28, 2015
3. ### Chemistry

Iodine 131 is a radioactive isotope. After 4.00 days, 70.8% of a sample of 131I remains.What is the half life of 131I?

asked by Natalie on April 26, 2014
4. ### math

You have just isolated a new radioactive element. If you can determine its half-life, you will win the Nobel Prize in physics. You purify a sample of 2 grams. One of your colleagues steals half of it, and eight days later you find

asked by Roseanne on October 21, 2012
5. ### science

A Geiger counter is used to measure the activity of a sample of iodine-131. Based on the data, what is the half-life of iodine-131? A. 16 days B. 8 days C. 4 days D. 12 days

asked by finley on August 20, 2016

More Similar Questions