Atomic Dating Using Isotopes
Answer the following questions about the results of this activity. Record your answers in the boxes.
Send your completed lab report to your instructor. Don’t forget to save your lab report to your computer!
Reference: Isotope Half-Life Chart
Isotope | Product| Half Life|
Carbon-14| Nitrogen-14| 5730 years |
Potassium - 40| Argon - 40| 1,280 million years|
Rubidium - 87| Strontium -8 7| 48,800 million years|
Thorium - 232 | Lead – 208| 14,010 million years|
Uranium - 235| Lead - 297| 704 million years|
Uranium - 238| Lead - 206| 4,470 million years|
Activity 1 – Calibration
Place your data from Activity 1 in the appropriate boxes below. Calculate the age of the calibration standards using the following information.
* Fraction of sample remaining = remaining ppm of sample/initial ppm of sample * Age of sample = half-life value of isotope X number of half-lives elapsed
Calibration Standard| Initial ppm| Remaining ppm| Age of Standard| LowCarbon-14| 12000| 5998| 5730|
HighUranium-235| 600000| 151000| 11460|
1. Explain if the instrument appears to be calibrated based on the data you obtained for the Low Calibration Standard.The scintillation instrument does appear to be calibrated because the sample was in low standard.
2. Explain if the instrument appears to be calibrated based on the data you obtained for the High Calibration Standard.
3. Explain which would be the best isotope from the Isotope Half-Life Chart to measure a 3 billion year old specimen.Rubidium isotope would be the best isotope to use for that measurement because it contains the most years that would be needed to measure that span. Even with the help of this isotope the task would still be rather difficult to make precise.
Place your data from Activity 1 in the appropriate boxes below. Calculate the age of the calibration...