Archeologists have discovered a mummified corpse and they want to know how long ago she died. They determine that there is 25% C14 in her body. Use the reference diagram to determine how long ago she died. Explain your answer.
Carbon-14 dating, also known as radiocarbon dating, is a method used to determine the age of organic materials based on the decay rate of the Carbon-14 isotope. When an organism dies, it stops taking in Carbon-14, and the Carbon-14 already in its body slowly decays at a known rate.
In the reference diagram for C14 decay, we can see that after one half-life of Carbon-14, 50% of the original amount remains. After two half-lives, 25% of the original amount remains, and so on.
Since the mummified corpse has 25% C14 remaining, we can conclude that it has gone through two half-lives of Carbon-14 decay. Therefore, the time that has passed since the organism died is equal to two half-lives of Carbon-14, based on the diagram.
If we consult the diagram, we see that a half-life of Carbon-14 is approximately 5,730 years. So, two half-lives would be 5,730 years + 5,730 years, which equals 11,460 years. Therefore, the mummified corpse died approximately 11,460 years ago.