Absolute Dating Worksheet The radioactive decay of the unstable isotope Potassiu
ID: 154213 • Letter: A
Question
Absolute Dating Worksheet The radioactive decay of the unstable isotope Potassium-40 (K-40) produces stable isotope Argon-40 (Ar-40) and has a half-life of 1.250 bilion years. K-40 is found in feldspar and mica minerals, as well as clays and rocks that contain potassium minerals. A sample initially contai 300,000 unstable K-40 atoms and no stable Ar-40 atoms. Complete the chart below to answer the following: a. How many K-40 atoms will be present after the first half-life? b. How many Ar-40 atoms will be present after the first half-life? c. How many K-40 atoms will be present after the second half-life? d. How many Ar-40 atoms will be present after the second half-life? How many K-40 atoms will be present after the third half-life? f. e. How many Ar-40 atoms will be present after the third half-life? g. How many years will have passed at the first half-life? h. How many years will have passed at the second half-life? i. Which isotope is the parent isotope? Which isotope is the daughter isotope? j. Time (by) Atoms of unstable isotope Atoms of stable isotope 0 300,000 0Explanation / Answer
Before answer this question let me introduce you to the concept of half-life. half-life is time taken by the parent element (k in your question) to decay by 50% into daughter elements. So if today let say potassium is 100 gm then after first half life it will remain only 50gm and in next half life if will remain only 25 gm and so on
Answer 1:150,000
answer2:150000
answer 3: 75000
answer 4: 225000
answer 5: 37500
answer 6: 262500
answer 7: 1.250 billion yr
answer 8: 2.500 billion yr
answer 9: potassium
answer 10:Argon
In case of Rb-Sr
answer 1: 48 million yr(since after 48 million yr the number of Rb has remain half)
answer 2:Rb
answer 3: Sr
answer 4: at 144 my three half-life passed so number of Rb remain is 50000
answer 5: 350000
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