I'm studying for a test and I can't grasp this half-life question.
Element C decays to Element D. You begin with 4400 atoms of Element C. After 20 years you have 275 atoms of Element C left.
A) how many atoms of element D are present after 20 years?
B) what is the half-life of element C?
thanks
Chemistry help?
2016-05-10 7:18 am
回答 (1)
2016-05-10 7:47 am
A)
Originally, there are 4400 atoms of element C, but no atom of element D.
1 atom of element C decays to give 1 atom of element D.
After 20 years :
Number of atoms of element D present = 4400 - 275 = 4125
B)
Let n be the number of half-lives in 20 years.
Fraction of atoms of element C left :
(1/2)ⁿ = 275/4400
(1/2)ⁿ = 1/16
(1/2)ⁿ = (1/2)⁴
n = 4
Half-life = (20 years) / 4 = 5 years
Originally, there are 4400 atoms of element C, but no atom of element D.
1 atom of element C decays to give 1 atom of element D.
After 20 years :
Number of atoms of element D present = 4400 - 275 = 4125
B)
Let n be the number of half-lives in 20 years.
Fraction of atoms of element C left :
(1/2)ⁿ = 275/4400
(1/2)ⁿ = 1/16
(1/2)ⁿ = (1/2)⁴
n = 4
Half-life = (20 years) / 4 = 5 years
收錄日期: 2021-04-18 14:48:22
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