Question

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 first-order 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 half-life of the radioactive decay.

Answer 1

k=0.693/t(1/2). Solve for t(1/2)

Answer 2

What order do you think this is?
From there use that information and find the half life equation.
Then just plug it in to get the answer

Hope that helps!