HALF LIFE

WHAT IS A HALF LIFE?

WHY DO WE NEED TO SOLVE HALF LIFE PROBLEMS?

STEPS TO SOLVING OUT HALF LIFE PROBLEMS

• Determine # of half lives.
• Plug values into the formula (1/2)^half lives * # of grams
• If you are working backwards, use (2) instead of (1/2) in the formula

Half-life example problems
The half-life of Zn-71 is 2.4 minutes, if you started with 100.0g how many grams would be left after 7.2 minutes?

If we follow our first step we find that Zn-71 has a half-life of 3(7.2/2.4) we then plug in our half life and find what remains is 12.5g we solved this by using (1/2)^3 * 100

Let's do this problem together
10g of iodine-131 is given to a patient. after 24 days, how many grams are left considering the half-life of iodine-131 is 8 days?

Quiz Time!
First person to answer this question correctly gets a piece of candy!

A batch of technetium -99 contains 200g the half-life of Technetium-99 is 6 hours, how many grams will remain after 24 hours?