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How many milligrams of a 15.0 mg sample of radium-226 remain after 6396 years if the half-life of radium-226 is 1599?
Wiki User
∙ 12y ago
One sixteenth of a gram. 1st halflife- 1/2 gram 2nd, 1/4 3rd 1/8th 4th halflife, 1/16th
Edwin Mitchell
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∙ 15y agoThe half-life of a radioactive element is the amount of time it takes for half the amount of a sample to undergo radioactive decay and become something else. The half-life of radium-226 is about 1602 years, so the question, which asks after the change in 800 years actually asks about "half a half-life" of a 2.5 gram sample. We don't need a calculator because we're going to round off. If half a 2.5 gram sample changes in 1600 years, that would be 1.25 grams. If "half the half-life" is waited out instead of a "whole half-life" is waited, half that will disappear, which is about 0.63 grams.
Wiki User
∙ 13y agoThe 4860 years represents three half-lives of radium-226. (It has a half-life of 1620 years, as stated. After one half-life, 12 grams of the original sample will remain. After another half-life, 6 grams will remain. (That's 3240 years gone by.) Finally, after a third half-life goes by (the 4860 years), 3 grams of the original 24 gram sample of radium-226 will remain.
Wiki User
∙ 12y agoIf the half-life of radium-226 is 1599 years, then 6396 years is four half-lives. After four half-lives, 0.0625 of a sample will remain, so 0.9375 of the 15 mg sample will remain after 6396 years.
Wiki User
∙ 12y agoHalf-life is the length of time that one half of the activity of a radioisotope will decay. It is a logarithmic process, so after successive half-lives, 1/2, 1/4, 1/8, 1/16, etc. will remain.
The half-life of 226Ra is 1600 years. 4800 years is 3 half-lives, so there would be 1/8, or 0.125, remaining of the 120g, or 15g.
Wiki User
∙ 13y agoAfter the 1st half life = 0.5 * 15g or 7.5 g
After the 2nd half life = 0.5*7.5 = 3.75g
After the 3rd half life = 0.5*3.75 = 1.875 g
Wiki User
∙ 14y agoHalf life period of the sample=1620 yrs total time=3240yrs no of half lives =3240/1620=2 after first halflife remaining sample=5gm after secnd halflife remaining sample=2.5 gms
Wiki User
∙ 12y ago4860 years represents three half-lives of radium-226, so 1/8 or 0.125 of that 1 gram sample would remain after 4860 years.
Wiki User
∙ 14y agoapprox. 4 000 years.
Wiki User
∙ 12y ago.03125
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