5. 1H + 31H To calculate half-life of a substance, you take the mass (in grams) of the substance and divide it by 2%, where x
= the number of half-lives passed.
For example, if I have a mass of 5 g sample of radioactive material and 4 half-lives pass, 5g/(24) = 0.31 g
Calculate the following:
6. The half-life of cobalt-60 is 5 years. If you have 10 grams of Co-60, how much do you have after 15 years?
7. The half-life of protactinium-226 is 2 minutes. If you started with 20 grams of Pa-226, how much do you
have after 8 minutes?