Chemistry
posted by Matt .
The age of a rock can be estimated by measuring the amount of 40Ar trapped inside. The calculation is based on the fact that 40K decays to 40Ar by a firstorder process. It also assumes that none of the 40Ar produced by the reaction has escaped from the rock since it was formed.
40K + e > 40Ar k = 5.81 X 10^11 year^1
Calculate the halflife of the radioactive decay.
Respond to this Question
Similar Questions

Geology
I need help with a radiometric dating equation. I am trying to determine the age of a sample that has a 40AR/40K ratio of 4.5. I understand the equation of D=Do+N(e^.693t1). I understand I would set Do to zero. But what is D? 
College Geology Homework
Suppose you have a sample of potassium feldspar from a rhyolite and you measure the ratio of atoms of 40Ar to 40K of 0.024 to 1, or for every 10000 atoms of 40K you find 240 atoms of 40Ar. For this problem, consider the decline of … 
Math/Radioactive Dating
How would I calculate the age of a rock only given the amount of each in grams and halflife? 
Math/Radioactive Dating
My teacher said that if the ratio of mass (in a rock) for 40K and 40Ar was 1:3 then the age of the rock would be 2.5 billion years. I don't understand how he concluded that to be the age. The only thing he knew was that the halflife … 
Chemistry 1046
Geologists can estimate the age of rocks by their uranium238 content. The uranium is incorporated in the rock as it hardens and then decays with firstorder kinetics and a halflife of 4.5 billion years. A rock contains 65.7% of the … 
Chemistry
Geologists can estimate the age of rocks by their uranium238 content. The uranium is incorporated in the rock as it hardens and then decays with firstorder kinetics and a halflife of 4.5 billion years. A rock is found to contain … 
Chemistry
Three isotopes of Argon occur naturally: 36Ar (mass = 35.9675 amu) 38Ar (mass = 37.9627 amu) 40Ar (mass = 39.9624 amu) If the percent abundance of 36Ar is 0.3400, what is the percent abundance of 40Ar? 
Physics  Half Life Question Check!!!
An ancient rock is found to contain 40Ar gas, indicating that 77% of the 40K in the rock has decayed since the rock solidified. Any argon would have boiled out of liquid rock. How long ago did the rock solidify? 
URGENT! Due soon and I used 8 of 10 attempts
Archaeologists can determine the age of artifacts made of wood or bone by measuring the amount of the radioactive isotope 14C present in the object. The amount of isotope decreases in a firstorder process. If 14.5% of the original … 
astronomy
The isotope potassium40 (40K) decays into the isotope argon40 (40Ar) with a halflife of 1.25 billion years. Suppose we find a rock in which seveneighths of the potassium40 has decayed to become argon40, and only oneeighth of …