Answer the following questions about the results of this activity. Record your answers in the boxes. Send your completed lab report to your instructor. Dont forget to save your lab report to your computer Reference Isotope Half-Life Chart Isotope ProductHalf LifeCarbon-14Nitrogen-145730 years Potassium – 40Argon – 401,280 million yearsRubidium – 87Strontium -8 748,800 million yearsThorium – 232 Lead 20814,010 million yearsUranium – 235 Lead – 297704 million yearsUranium – 238 Lead – 2064,470 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 Low Carbon-14 High Uranium-235 Explain if the instrument appears to be calibrated based on the data you obtained for the Low Calibration Standard. Explain if the instrument appears to be calibrated based on the data you obtained for the High Calibration Standard. Explain which would be the best isotope from the Isotope Half-Life Chart to measure a 3 billion year old specimen.

Activity 2 Place your data from Activity 1 in the appropriate boxes below. Calculate the age of the calibration standards using the following information. The initial carbon-14 content of the tree specimen is 6 of the carbon-12 content of the specimen. The initial carbon-14 content of the insect specimen is 8 of the carbon-12 content of the specimen. The initial carbon-14 content of the bat specimen is 8 of the carbon-12 content of the specimen. Formulas Estimated initial carbon-14 content of carbon-12 ppm value (from above) X carbon-12 in specimen/100 Fraction of carbon- 14 remaining in sample remaining ppm of sample/initial ppm of sample Age of sample half-life value of carbon-14 X number of half-lives elapsed Sample Carbon-14 ppm Carbon-12 ppm Estimated Initial Carbon-14 Estimated Age of Specimen Tree Fossil Specimen Insect Fossil Specimen Bat Fossil Specimen Explain how you obtained the estimated initial value of the carbon-14 content. Describe if the age of the each specimen is likely a realistic value. You will need to use the web to evaluate the approximate age of the oldest specimen that is possible for trees, insects, and bats.