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The Dating Game data | hook | main | background & resources | student Procedure 1. Place the candies in the box "M" side down. 2. Close the cover and shake - not too vigorously! 3. Open the box and remove all the "changed" candies.(Those that are "M" side up) 4.Count and record the number of "unchanged" candies remaining in the box. Record this data in a table which you design. 5.Repeat steps 2, 3 and 4 until all the candies have turned. 6.Graph the information from the chart. What kind of graph will best display this kind of data? Bar? Line? Why? Discussions Questions/Extensions ...... Can you think of a way that half-lives could be used to determine the absolute time of geological events like volcanic eruptions? Can you think of ways that half-lives could be used to determine biological events? Radioactive Decay of Carbon-14
I. Teacher Discovers Death in Wright Valley, Antarctica On January 27, 1999 Tulley stumbled upon a mummified seal in Wright Valley. Although the seal was intact and appeared in good condition (for a dead seal!) the leathery appearance of the skin made all in the expedition wonder about how this seal came to be so far from the sea. How long had this seal been dead? Eventually the scientists requested a 14 C radiometric dating test done on the seal's body. To their astonishment the test found that for every 100,000,000 12C atoms present in the seal's body,4,100 radioactive 14 C atoms were present, instead of the 10,000 atoms expected for a recently deceased seal. 14C half-life is approximately 5,700 years. Using your knowledge of half-life from yesterday's lab create your own table graph and solution to the problem. How long ago did the seal die? _________________________. Go to Tulley journal for January 27, 1999 (../../tulley/1.27.199.html) to see if you were right! II. Murder Above the Arctic Circle The body of a man wearing the traditional clothes of the Saami people was found at the bottom of one of the many peat bogs that remain from the last glacial retreat. Buried in the back of his skull was a stone ax, made in the archaic style. The stone ax head was sharpened by chipping and the head was bound to a forked wooden handle by crisscrossed hide strips. Bog acid has tanned the man's skin. Although his skin is wrinkled and tightly drawn over hex facial bones, he is still distinguishable aand his clothes and internal organs are still intact and available for police analysis. The withered condition of the body has convinced the police that the homicide happened at least 10 yeas ago. From forensic evidence, we can conclude that he was murdered in a different place, dragged to the bog and tossed in. After months of investigation no new evidence or information was turned up Eventually the police requested a 14C radiometric dating test done on the victim's body and clothes.To their astonishment the test found that for every 100,000,000 12C atoms present in the man's body, and clothes only 3,000 radio-active 14C atoms were present, instead of the 10,000 atoms expected for a recently deceased person. This has greatly confused the police who had assumed that the murder was a recent event. How long ago did the murder take place? _________________________. 14 C half-life is approximately 5,700 years. Using your knowledge of half-life from yesterday's lab create your own table graph and solution to the problem. How long ago did the murder take place? _________________________.
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