# Is the half-life of Primordial Nuclide determine only by the age of the earth? [closed]

Is the half-life of Primordial Nuclide determined only by the age of the earth? Or are their other age defining considerations? The point of the question is to know that the only reason that we have a determination of the half-life of Primordial Nuclide is by its comparison solely to the lifespan of the earth, or if their is any other foundation for determining the half-life.

I want an alternate method of determining the duration half-life of a Nuclide. Specifically Primordial Nuclide. The only method that I know about right now is through visual measurement.

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## closed as unclear what you're asking by rob, Brandon Enright, Jim, John Rennie, Chris WhiteJun 27 '14 at 23:51

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The half-life of any nuclide is independent of the age of earth; it is what it is. – Kyle Kanos Jun 27 '14 at 16:30
@rob That question is to find the "How" to a considered radioactive decaying process. This question is related to "When/Duration". And the measurement of that duration. So you are in error. – Decrypted Jun 27 '14 at 17:16
@KyleKanos What you say is true. The point however is "NOT" to redeem a value to a half-life by the equation (Time of Earth Creation)+(Lifespan of Earth)=half-life of Primordial Nuclide. But by another means to determine its lifespan. It may be what it is, yet Nuclides with half-lives less than 24 hours but more than 1.0 hour do exist and can be proven by visual results. Therefore what is seen stands as its own testimony, for others can see it as-well. With Primordial Nuclide we have a visual record as-well but it should not stand with the same testimony for what test visually proves duration? – Decrypted Jun 27 '14 at 17:28
I have no idea what message your comment to me is trying to convey (it seems to be completely irrelevant to my comment). – Kyle Kanos Jun 27 '14 at 17:32

## 1 Answer

An age estimate of the Earth is not used to determine half-life of an isotope.

Instead, the rate of decay (decays per time unit) relative to the amount of sample (number of nuclei), and first order kinetics are used to determine half-life.

For example, in 1932 Kovarik and Adams calculated the Uranium-238 half life based upon 24,770 alpha particle decays per second per gram of uranium.

See The Isotopic Constitution of Uranium and the Half-Lives of the Uranium Isotopes. I and references cited therein for historical and experimental information.

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Is this method you speak of "first order kinetics" used to valuate this statement "Around 99.284% of natural uranium is uranium-238, which has a half-life of 1.41×1017 seconds (4.468×109 years, or 4.468 billion years)" Found (en.wikipedia.org/wiki/Uranium-238)? – Decrypted Jun 27 '14 at 18:12
It applies to the "uranium-238, which has a half-life of 1.41×1017 seconds (4.468×109 years, or 4.468 billion years)" part, but it is unrelated to the "Around 99.284% of natural uranium is uranium-238" part of the statement. – DavePhD Jun 27 '14 at 18:16
I accept this answer not because I know its the truth, but because it fulfills the format of the question. – Decrypted Jun 30 '14 at 15:01
@Onlyheisgood. see the following publication of Rutherford's 1899 measurement of Thorium's half-life: chemteam.info/Chem-History/Rutherford-half-life.html This is a good example of how half-life is experimentally determined. – DavePhD Jun 30 '14 at 15:10
@Onlyheisgood. I added a reference that explains in more detail how Uranium-238 half life was first determined. – DavePhD Jul 1 '14 at 13:54