Question

2. Your lab requires you to keep track of the Radioactive Material: Each Month you must record what has been used and how much remains. No one has removed any of the isotopes. How much was there on Feb 1? on March 1? 31 days in January 28 days in February Isotope Half-life Jan 1 Feb 1 March 1 100μCi 31 32p 14.29 days 28 355 86.35 days 1mCi 31 100uci- HalFlife 1429Days

Answer 1

Isotope	Half-life	Jan 1	Feb 1	March 1
32P	14.29 days	100 uCi	22.23 uCi	5.72 uCi
35S	86.35 days	1 mCi	0.78 mCi	0.62 mCi

Explanation

According to radioactive decay law,

final amount = (initial amount) / (2^a)

where a = half-lives passed

(1.) For isotope ³²P,

initial amount = 100 uCi

time passed till Feb 1 = 31 days

half-lives passed = (time passed till Feb 1) / (half-life)

half-lives passed = (31 days) / (14.29 days)

half-lives passed = 2.17

Substituting the values,

final amount of ³²P = (100 uCi) / (2^2.17)

final amount of ³²P = (100 uCi) / (4.5)

final amount of ³²P = 22.23 uCi

(2.) For isotope ³²P,

initial amount = 100 uCi

time passed till March 1 = (31 days) + (28 days)

time passed till March 1 = 59 days

half-lives passed = (time passed till March 1) / (half-life)

half-lives passed = (59 days) / (14.29 days)

half-lives passed = 4.13

Substituting the values,

final amount of ³²P = (100 uCi) / (2^4.13)

final amount of ³²P = (100 uCi) / (17.5)

final amount of ³²P = 5.72 uCi