1. Uses of Nuclear Chemistry (and half life post lab)

2. Half Life
Def:
Time it takes for the amount of a radioactive substance to decay by half

3. Penny Lab Class Data
How many nondecayed pennies were left over after 2 half lives?
How many nondecayed pennies were left over after 5 half lives?

4. Example Problem
The half-life of Po-218 is three minutes. How much of a 2.0 gram sample remains after 15 minutes?

5. Another Example Problem
The half-life of Ar-42 is eleven minutes. How much of a 5.0 gram sample remains after 55 minutes?

6. One More Example Problem
The half-life of Na-20 is 30 minutes. How much of a 3.0 gram sample remains after 90 minutes?

7. A Different Type of Problem
The half-life of isotope X is 2.0 years. How many years would it take for a 4.0 mg sample of X to decay and have only 0.50 mg of it remain?

8. One More…
The half-life of isotope J is 2.5 months. How many years would it take for a 8.0 g sample of J to decay and have only 0.25 mg of it remain?

9. Ok, last one….
The half-life of isotope Z is 7.0 years. How many years would it take for a 24.0 mg sample of Z to decay and have only 12.0 mg of it remain?