Radiometric Dating Lab: Carbon-14 and Uranium-238, Study Guides, Projects, Research of Physics

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Radiometric Dating Game (LAB) - 14062128

Physics (Norwalk High School (California))

Radiometric Dating Game (LAB) - 14062128

Physics (Norwalk High School (California))

Name ______________________________________________________ Period ______ Date _________

Radioactive Dating Game Lab

http://phet.colorado.edu/simulations/sims.php?sim=Radioactive_Dating_Game Run CheerPJ browser compatible version

Purpose: You will use the radioactive decay rate and original-daughter element ratios of carbon- and uranium-238 to determine the ages of different objects.

Procedure:

1. Load PhET Radioactive Dating Game
2. Click on tab for Decay Rates
3. Select Carbon-14. Using the graph, the estimated half-life for C-14 is 6,000 years.
4. Move the bucket slider all the way to the right. This will place 1000 C- atoms onto the screen. a. Click on the Start/Stop to stop the C-14 decay. Click on Reset All Nuclei b. Click on the Start/Stop to start the C-14 decay. Stop the decay as you get close to one half-life. c. Use the Step button to stop decay at one half-life. ● After 1 half-life, how many C-14 atoms of the 1000 original remain? 502 d. Use the Start/Stop and Step buttons to reach two half-lives. After two half-lives, how many C-14 atoms remain? 227 ● What fraction of C-14 atoms present at 1 half-life remain after 2 half-lives? 50% e. Use the Start/Stop and Step buttons to reach three half-lives. After three half-lives, how many C-14 atoms remain? 114 ● What fraction of C-14 atoms present at 2 half-life remain after 3 half-lives? 50% f. Repeat Steps (a) to (e) with uranium-238. ● Estimated half-life for U-238 is 5 billion years. ● After 1 half-life, how many U-238 atoms of the 1000 original remain? 513 ● What fraction of U-238 atoms present at 1 half-life remain after 2 half-lives? 50% ● What fraction of U-238 atoms present at 2 half-life remain after 3 half-lives? 50% ● Based on the results of 4a to 4f , explain the meaning of the word “ half-life ” in one sentence. Half-life is the time needed for half of an element to decay into another element.

Table: Radiometric Ages for Various Objects

Object Measured using C-14 or U-238?

% of Original

Guessed Age

Measured Age Animal Skull C-14 98.2% 151 yr 151 yr

Living Tree C-14 100% 0 yr 0 yr

Distant Living Tree C-14 100% 0 yr 0 yr

House C-14 99.1% 72 yr 72 yr

Dead Tree C-14 97.4% 211 yr 211 yr

Bone C-14 83.9% 1483 yr 1483 yr

Wooden Cup C-14 88.2% 1046 yr 1046 yr

1 st^ human skull C-14 76.6% 2199 yr 2199 yr

2 nd^ human skull C-14 0.8% 40075 yr 40075 yr

Fish Bones C-14 14.4% 16022 yr 16022 yr

Fish Fossil 1 C-14 0.0% 57,250 yr?

Rock 1 U-238 97.9% 149.21 MY 149.21 MY

Dinosaur Skull C-14 0.0% 194.21 MY 194.21 MY

Rock 2 U-238 96% 242.02 MY 242.02 MY

Trilobite U-238 0.0% 242.02 MY 242.02 MY

Rock 3 U-238 93.3% 443.35 MY 443.35 MY

Rock 4 U-238 89.4% 706.15 MY 706.15 MY

Rock 5 U-238 82.3% 1.26 BY 1.26 BY