1. A granite rock is thought to be about 2 billion years old. why is it not possible to determine the age of the Rock using carbon-14 dating?
2. A hair sample has 80% of its original carbon-14 present. what is the age of the sample?
3. A bone fragment has lost 75% of its original carbon-14. what is the age of the bone fragment?
4. an organic sample is 28,650 years old. what percent of the original carbon-14 still present in the sample?
The half live of C14 is only about 6,000 years and this is not suitable to a rock sample of that age. There is a section is the link below that talks about which methods are best for various ages.
http://en.wikipedia.org/wiki/Radiometric_dating
2. k = 0.693/t1/2
Look up t1/2 in your text or notes and solve for k.
Then ln(No/N) = kt.
Set No = 100
N = 80
k from above
Solve for t.
#3 is the same process as #2.
4. ln(No/N) = kt
No = 100
N = x
k from above
t = 28,650 years.
Solve for N and convert to the percentage to the starting 100.
2 years
1. Carbon-14 dating is not suitable for determining the age of a granite rock that is estimated to be 2 billion years old. Carbon-14 dating is primarily used for estimating the age of organic materials that were once living. This is because carbon-14 is a radioactive isotope that decays over time. Organic materials absorb carbon-14 from the atmosphere while they are alive, and the carbon-14 slowly decays after the organism dies. By measuring the remaining amount of carbon-14 in a sample, scientists can estimate its age.
However, granite rocks are igneous rocks that form from solidified magma or lava, and they do not contain any organic material. Therefore, there is no carbon-14 present in granite rocks to measure and determine their age using carbon-14 dating. To determine the age of granite rocks, scientists use other dating methods, such as radiometric dating using isotopes like uranium-lead or potassium-argon.
2. If a hair sample has 80% of its original carbon-14 present, it is possible to estimate its age using carbon-14 dating. Carbon-14 has a half-life of approximately 5730 years, meaning that after this time, half of the carbon-14 initially present in a sample will have decayed. By measuring the amount of remaining carbon-14 and comparing it to the amount expected in a freshly created sample, scientists can calculate the age.
To determine the age of the hair sample, we need to know the half-life of carbon-14 and how much carbon-14 was present in a freshly created sample. Since the question does not provide the latter information, it is not possible to calculate the exact age of the sample.
3. Similarly to question 2, it is not possible to determine the actual age of the bone fragment without knowing the half-life of carbon-14 and the initial amount of carbon-14 present in a freshly created sample. However, we can calculate the approximate age relative to the original amount of carbon-14.
If a bone fragment has lost 75% of its original carbon-14, it means that 25% of the original carbon-14 is still present. This remaining amount of carbon-14 can be compared to the expected amount in a freshly created sample to estimate the age relative to when the bone was alive.
4. If an organic sample is 28,650 years old, the percent of the original carbon-14 still present in the sample can be calculated based on the half-life of carbon-14.
Since the half-life of carbon-14 is approximately 5730 years, we can calculate the number of half-lives that have passed since the sample was created. In this case, the number of half-lives would be 28,650 divided by 5730, which is approximately 5.
Each half-life halves the amount of carbon-14, so after 5 half-lives, the remaining amount of carbon-14 would be (1/2)^5, which is equal to 1/32 or approximately 0.03125.
To convert this into a percentage, we multiply by 100, so the remaining amount of carbon-14 in the sample would be approximately 3.125% of the original.