Day 6: Problems

Your goal is to try to answer the problems found below.  For each one you can use a hand-drawn chart like this one, or the table that is attached, but you MUST show your logic for each project.  Just writing down the answer will not get you credit.

1) The half life of iodine-131 is 8.040 days. What percentage of an iodine-131 sample will remain after 40.2 days?
2) The half-life of thorium-227 is 18.72 days How many days are required for three-fourths of a given amount to decay?
3) If you start with 5.32 x 10⁹ atoms of Cs-137, how much time will pass before the amount remaining is 5.20 x 10⁶? The half-life of Cs-137 is 30.17 years.
4) The half-life of the radioactive isotope phosphorus-32 is 14.3 days. How long until a sample loses 99% of its radioactivity?
5) U-238 has a half-life of 4.46 x 10⁹ years. How much U-238 should be present in a sample 2.5 x 10⁹ years old, if 2.00 grams was present initially?   (Hand this in individually)

Part 2:  Radon.  Radon is a big problem in Iowa, and the videos we watched in the last post point this out.   Design some sort of a Public Service Announcement that will highlight this concern to people in Iowa, why it is dangerous, and what they can do about it.

Part 3:  Radioactive Dating as a Group

Click to Run

Use the applet above to complete as much as you can with your group of this document   Save it to a Google Docs folder and share it with me.