Uranium isotope relative abundance at diff times

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SUMMARY

The discussion focuses on calculating the relative abundance of uranium isotopes (238U, 235U, and 234U) at the time of Earth's formation, approximately 4.6 billion years ago. The current abundances are 99.2745% for 238U, 0.7196% for 235U, and 0.0055% for 234U. Participants suggest using the decay equations, specifically t = age = 1/lambda * ln(N/No) and N = No*e^lambda*t, to reverse-engineer the isotopic ratios based on their half-lives. The approach involves determining the half-lives of the isotopes and applying these to estimate their original abundances.

PREREQUISITES
  • Understanding of radioactive decay and half-lives
  • Familiarity with the decay equations: t = 1/lambda * ln(N/No) and N = No*e^lambda*t
  • Knowledge of uranium isotopes: 238U, 235U, and 234U
  • Basic grasp of logarithmic functions
NEXT STEPS
  • Research the half-lives of uranium isotopes: 238U, 235U, and 234U
  • Learn how to apply radioactive decay equations in practical scenarios
  • Explore the concept of isotopic dating in geology
  • Investigate the decay products of uranium isotopes, particularly Thorium
USEFUL FOR

Students in geology, nuclear physics, and anyone interested in understanding radioactive decay and isotopic abundance over geological time scales.

thiev
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Homework Statement



The relative abundance of uranium isotopes in today’s Earth crustal material is:
99.2745% 238U
0.7196% 235U
0.0055% 234U
What were the relative abundances when the Earth was formed 4.6x109 years ago?


Homework Equations



t = age = 1/lambda * ln(N/No)

N = No*e^lambda*t

The Attempt at a Solution



i don't know how to approch this...
 
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Welcome to PF.

What are the half-lives of the 3 isotopes?

Since they all decay to Thorium then maybe if you work them backwards you can turn back the clock to see what was around 4 and a half billion years ago?
 

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