Half-Life Homework (Web Help) All hints, pointers, and examples are in blue
The
graph below shows the decay of
1. What type of decay particle does
2. How long did it take for the mass of the sample to be
reduced to 50% of its original value? Half of 60 g is 30 g,
how long did that take? (see graph)
3. How long did it take for the mass of the sample to be reduced
to 25% of its original value? See purple line on graph
4. How long did it take for the mass of
the sample to be reduced from 50% of its original
value to 25% of its original value?
5. What is the half-life of
the sample to
decay to the daughter isotope
6. If a sample originally had of 3.8 g of
how old is the sample? Use the table in your notes to determine the number of
half-lives,
then multiply by
the length of each half-life
7.
information above, why do you think there isn’t any
naturally occurring
Hint: the earth
is 4.5 billion years old…
8. Why would it be worse to handle the
sample the first week than the second or third
week? The danger is the
amount of particles given off by the sample…
The
graph below shows the decay of
9. What type of particle is emitted by
The mass went down by 4, so what would than mean?
10. What is the half-life of
11. How
long would it take for 120g of
and 105g of
12.
Approximately how long would it take
for a 1000g sample to be reduced to 1 g?
(hint: count how many times you have
to divide the sample in half, then consider the
length of each half-life)
1 ¸ 1000 = .001
which is equivalent to 10 half-lives, so multiply the half-life by 10
13. Living organisms bring in
7.5 ´ 10-5 g ¸ 2.4 ´ 10-3 g = .03125 consult your table to find how many
half-lives this is
14. Why do you think that